The O.C., The Complete Series

Tough, troubled teen Ryan is invited to stay in wealthy Newport Beach and meets dreamer Seth and beautiful girl next door Marissa, whose rich father is up to no good.

Kirsten doesn't want Ryan permanently, so he buys a bus ticket. Ryan, Seth and Marissa hide in a model home, but Summer finds out and causes trouble with a bully who fights Ryan.

Kirsten takes temporary custody of Ryan. Jimmy borrows money from Kirsten. Summer uses Seth for good luck at a casino benefit. Ryan's mom drunkenly embarrasses him and then leaves.

Ryan is matched with Anna for cotillion, but he ends up taking Marissa. Summer abandons her intended escort, Seth. Jimmy admits his financial trouble. A fight happens at the event.

Ryan protects Seth at a party in a bad neighborhood. Ryan again must save him after Seth invites the same people to a party in Newport. Luke is shot. Broke Jimmy has a hard choice.

Kirsten has trouble working for her driven father. Julie demands a divorce. After Caleb's hot girlfriend seduces Ryan, Marissa has sex with Luke, who is nicer since being shot.

While Kirsten and divorcing Jimmy paint his new home, they kiss. Sandy considers a job. In Tijuana with the other teens, Marissa finds out about her parents' divorce and overdoses.

Sandy takes a lucrative new job for an attractive woman, which bothers Kirsten. Ryan leaves a placement test in order to help Seth and Summer save Marissa from being sent away.

Summer is secretly jealous of Seth's relationship with Anna. Sandy works on a lawsuit against Caleb's company, bothering Kirsten even more. Ryan fights with Luke over Marissa.

Marissa and Ryan begin dating. Summer tries to deny her feelings for Seth as he gets closer with Anna. Kirsten and Sandy continue to clash. Julie reveals a new relationship.

Seth gets in trouble choosing between Summer and Anna. It's a Thanksgiving to remember as Ryan takes Marissa to visit his brother in prison while angry Julie and the others wait.

Anna and Summer are upset with Seth. Julie has love problems. Sandy helps Jimmy with legal issues. Kirsten's indiscretion is exposed. Ryan and Luke form an unexpected alliance.

Seth introduces Chrismukkah, a Cohen family tradition combining Kirsten's Christianity and Sandy's Jewish heritage. Seth juggles two girls. Kirsten's issues with her father worsen.

Kirsten's rebellious sister causes turmoil by hosting a huge party in the Cohens' house on New Year's Eve. Marissa goes to another party, but Ryan rushes to kiss her at midnight.

Disruptive Hailey refuses to leave the Cohen house. Seth chooses Anna. Ryan is jealous of Marissa's troubled new friend, Oliver. But Ryan later helps Oliver get out of trouble.

Summer tries to annoy Seth and Anna. Oliver irritates Ryan. When Oliver almost overdoses, Marissa stays with him. Hailey moves out. Jimmy and Sandy go into business together.

Sandy and Jimmy buy a restaurant. Kirsten and Julie become workmates. Seth's jealousy of Summer's new boyfriend gives him doubts about dating Anna. Ryan loses control over Oliver.

Caleb forces Kirsten to terminate Julie. Sandy and Kirsten question taking in Ryan. When Ryan and Luke ally to protect Marissa from Oliver, she discovers the truth about him.

Marissa tries to reconcile with Ryan, but he can't forgive her for Oliver. Ryan's ex-girlfriend from Chino arrives for Valentine's Day. Seth and Summer escalate their friendship.

Marissa and Ryan try to start over as friends. Theresa wasn't honest about why she's in Newport. Summer won't acknowledge Seth at school. Sandy is in another mess created by Caleb.

Ryan is glad Theresa will stay in Newport. Julie and Luke's secret affair is threatened when Jimmy sees them. When Anna plans to move back to Pittsburgh, Seth tries to stop her.

Summer loves being with an actor (COLIN HANKS), to Seth's chagrin. But Summer minds when Seth meets a sexy girl (PARIS HILTON). Ryan hides Luke and Julie's affair from Marissa.

When Sandy's mother (LINDA LAVIN) visits, Seth fears she'll disapprove of Summer, who tries to prove him wrong. Marissa runs off when she finds out about Luke and Julie's affair.

Marissa is still mad at Julie and Luke. Luke gets in a near-fatal accident. Sandy makes a choice when he can't get a liquor license because of Jimmy. Caleb proposes to Julie.

Julie has a memorable wedding shower. Theresa returns, and when Ryan finds out why, he is shocked. Seth gets the chance to meet Summer's father, but it doesn't go very well.

Seth and Ryan help Caleb celebrate in Las Vegas, while Kristen reluctantly plans a bachelorette party for Julie. Marissa learns something about Teresa that could have consequences.

Julie's wedding day will long be remembered. It's only the beginning of a series of events that will change many lives in Orange County forever. JEM performs at the ceremony.

The lives of a group of friends and families have been forever changed by the arrival of an outsider to their affluent oceanside community of Newport Beach in Orange County, California. When Ryan Atwood (series star BENJAMIN McKENZIE) was taken in from the streets of Chino by then public defender Sandy Cohen (series star PETER GALLAGHER), the Cohens had no idea how Ryan's arrival would affect them and those around them. Initially resistant, Kirsten (series star KELLY ROWAN) opened her heart to accept the outsider just as she had accepted Sandy, another outsider, into her old-money Newport Beach family. In Ryan, their "adorkable" son, Seth (series star ADAM BRODY), found a friend and brother with whom he could share his quirky way of looking at the world. Seth also struggles with the trials and tribulations of winning the heart of Summer Roberts (series star RACHEL BILSON), his lifelong crush.

Summer is over, and school is in session. Seth and Ryan hope to win back the attention they once had from Summer and Marissa. With opportunity beckoning, Hailey (recurring guest star AMANDA RIGHETTI) tells Jimmy about her plans to move in order to pursue her unfulfilled fashion ambitions. Hoping to keep her near, Jimmy does something unimaginable. Meanwhile, Sandy explains to Julie that the district attorney is keeping a close watch on Caleb, and without representation, he might be in for a confrontation. Julie threatens Sandy to do something about Caleb's messy situation or face her wrath.

At the Bait Shop, the new music club on the pier, Seth gets some help from his attractive and tough-talking manager, Alex (recurring guest star OLIVIA WILDE - "The Girl Next Door," "Skin"), to prove that his friends don't know him as well as they think. Meanwhile, Summer gives some thought to how she really feels about Seth after she learns more information about her new boyfriend, Zach (recurring guest star MICHAEL CASSIDY). Marissa is happy to share an evening with Ryan. But at school, Ryan is embarrassed and frustrated after a confrontation with new classmate Lindsay (recurring guest star SHANNON LUCIO). Caleb's legal problems threaten to leave both Sandy and Kirsten unemployed as Julie makes sure she stays in power--even if Caleb is ruined.

Seth, who is now without a girlfriend, and Sandy, who has just been fired from the law firm, embark on new eras in their lives and vow to take the whole family with them. Ryan and Seth go on an awkward double date to see THE KILLERS (themselves) perform at the Bait Shop, with unexpected results. Meanwhile, Julie finds herself overwhelmed by her new role at the Newport Group and, as usual, is forced to turn to Kirsten for help.

The winter season finally comes to Newport, and Seth, Ryan, Summer and Marissa attend the annual SnO.C. Winter Ball. Julie and Jimmy spend some quality time together as the chairs of the host committee, and Sandy gets closer to the truth Caleb has been hiding. Meanwhile, Julie discovers Marissa's secret when Marissa leaves school at lunch and goes home to meet D.J. (recurring guest star NICHOLAS GONZALEZ).

The whole gang is invited to Chrismukkah at the Cohens' house, but Seth's favorite holiday is nearly ruined as secrets are revealed that will change the Cohen family forever. Summer, Marissa and Ryan make a plan to save Chrismukkah.

Ryan tries to come to terms with his feelings for Lindsay (recurring guest star SHANNON LUCIO). Now that she may become a member of the Cohen family, their attraction is rather awkward. Although Sandy knows they're dating, Ryan and Lindsay keep the relationship hidden from Kirsten. Meanwhile, Caleb learns that the criminal charges against him have been dismissed. And in an effort to impress Alex (recurring guest star OLIVIA WILDE), Seth tries to cultivate a "bad boy" image by dressing like Ryan, getting drunk and stealing Caleb's prized sports car. Marissa sees Jimmy and Julie kissing aboard his boat and is hurt and angry with her father. Jimmy finally realizes that after all the trouble and heartache he's caused, the best thing he can do for himself and his daughter is to leave Newport and move to Maui...but not before a big going-away party at the Cohens' house.

Lindsay (recurring guest star SHANNON LUCIO) and Ryan grapple with their new relationship: Is Lindsay Ryan's step-aunt or his girlfriend? Meanwhile, Summer meets Zach's (recurring guest star MICHAEL CASSIDY) family, and it doesn't go so well. In the end it's an anniversary to remember as Sandy surprises Kirsten with a serenade at the Bait Shop. But Marissa ends up alone as D.J. (recurring guest star NICHOLAS GONZALEZ) leaves Newport Beach.

It's girls against boys when Marissa and Summer decide to plan a girls' night out and include Lindsay (recurring guest star SHANNON LUCIO) in the festivities. Left to their own devices Ryan, Seth and Zach (recurring guest star MICHAEL CASSIDY), have a bonding session over video games and pizza but find it hard to stay away from their female counterparts. Julie and Kirsten collaborate on an idea to help the image of the Newport Group while Sandy and Caleb try to convince them there may be a better way.

Seth and Zach (recurring guest star MICHAEL CASSIDY) decide to create a comic book based on their lives in Newport Beach. While browsing through the sketches, Summer wonders why she's been left out. Sandy decides to help an old friend, Professor Max Bloom (recurring guest star BARRY NEWMAN - "40 Days and 40 Nights," "Petrocelli"), find his daughter, Rebecca (recurring guest star KIM DELANEY - "CSI: Miami," "NYPD Blue"), but the search leads to even more questions. While Julie is away, Marissa's contempt for Caleb grows as she looks for new ways to rebel. Meanwhile, Ryan tries to help Lindsay (recurring guest star SHANNON LUCIO) satisfy her curiosity about Caleb.

Summer decides to take an active role in creating the comic book, but Seth doesn't know if he can handle spending that much time alone with her. Sandy and Rebecca (recurring guest star KIM DELANEY) reminisce about days gone by as Kirsten tries to convince Caleb that he could have a familial relationship with Lindsay (recurring guest star SHANNON LUCIO). Meanwhile, Caleb decides what kind of future he wants to have with his daughters. And Alex (recurring guest star OLIVIA WILDE) asks Marissa where their friendship is going. Chicago singer/songwriter RACHEL YAMAGATA performs.

Sandy tries to make amends with Kirsten for keeping Rebecca's (recurring guest star KIM DELANEY) return a secret by showering his wife with Valentine's Day gifts. Zach (recurring guest star MICHAEL CASSIDY), Summer and Seth drive to San Diego to pitch their comic book idea, and Seth is determined to use the trip to get Summer back. Julie returns from her European vacation and has decided to reconnect with Marissa. Meanwhile, Ryan wants to spend Valentine's Day with Lindsay (recurring guest star SHANNON LUCIO), but her loyalty to Caleb gets in the way.

While Rebecca (recurring guest star KIM DELANEY) pays her last respects to her father, Kirsten grows impatient with Sandy's long absences from home and decides to visit Rebecca. Alex (recurring guest star OLIVIA WILDE) invites Marissa to hang out with her friends. Meanwhile, Caleb decides to remove all doubt that Lindsay (recurring guest star SHANNON LUCIO) is his daughter.

It's raining in Newport. Marissa tells Julie that she and Alex (recurring guest star OLIVIA WILDE) are dating and decides she has to get out of Caleb's house. Summer is faced with a big decision as she prepares to go to Italy with Zach (recurring guest star MICHAEL CASSIDY). Ryan convinces Lindsay (recurring guest star SHANNON LUCIO) to take the paternity test, and everyone anxiously awaits the results. Meanwhile, Sandy is stranded in a motel room with nothing but a few snacks, champagne and Rebecca (recurring guest star KIM DELANEY).

Although she is trying hard to make her new living situation work, Marissa feels she needs a break and agrees to join Summer, Seth and Ryan at the mall. Julie and Kirsten await the arrival of Carter (recurring guest star BILLY CAMPBELL - "Enough," "The Rocketeer"), the new editor of Newport Living, but Julie is distracted when she's visited by Lance (recurring guest star JOHNNY MESSNER - "Spartan," "The Whole Ten Yards"), an opportunistic man from her past. Meanwhile, Sandy and Caleb finally bond over all of their recent experiences.

Seth is determined to bring back the spirit and fun times of last year and won't stop until his plan is successful. Alex's (recurring guest star OLIVIA WILDE) jealousy is fueled when Marissa enlists an unlikely partner to help her with the school bonfire. Meanwhile, Kirsten wants Carter (recurring guest star BILLY CAMPBELL) to continue with the magazine despite his reservations, and Sandy helps Julie keep her blackmailer at bay.

When someone from Ryan's past comes for a visit, he worries that nothing good can come of it; while the Cohen family welcomes the Chino visitor with open arms. As Marissa and Ryan continue to explore their newfound friendship, Seth and Summer face some unforeseen news. Meanwhile, Julie admits her mistake to Kirsten and looks to Caleb for help.

When Sandy becomes the honorary chairman of the Newport Beach charity yard sale, he solicits help from Trey (recurring guest star LOGAN MARSHALL-GREEN), who has his first confrontation with the Newpsies. While Sandy auctions off Newport's finest, Kirsten and Carter (recurring guest star BILLY CAMPBELL) share a table. When one of the auction's most expensive pieces goes missing, Ryan and Seth could also use some help. Meanwhile, Trey looks for a more permanent place to live as the Cohens welcome yet another houseguest.

Eager to help Trey (recurring guest star LOGAN MARSHALL-GREEN) and Ryan repair their relationship, Marissa hosts a birthday party for Trey at Caleb's mansion that quickly gets out of control. After surfing with Carter (recurring guest star BILLY CAMPBELL), Sandy suggests introducing him to a woman friend, to Kirsten's chagrin. When Summer finds out what Seth's potential graphic novel publisher, Reed (recurring guest star MARGUERITE MOREAU), is really like, Seth is in big trouble. And after leaving town in disgrace, Julie returns and surprisingly ends up reminiscing with an old acquaintance.

After the wild party at Caleb's mansion, Sandy, Seth and Ryan devise a plan to save another Atwood from going to jail. Kirsten and Carter (recurring guest star BILLY CAMPBELL), fulfilling more than their editorial duties, take a trip to the wine country. Meanwhile, Caleb returns from Europe and rebuffs Julie's romantic advances. The band DEATH CAB FOR CUTIE performs.

Sandy, Seth and Ryan travel to Florida to visit Seth's Nana, Sophie (recurring guest star LINDA LAVIN - "Alice"), who is living in Miami Beach. While playing shuffleboard at the coastal retirement community, Seth and Ryan meet Mary-Sue (JAIME KING - "Sin City"), who helps Seth get center stage on the Music Video Nation spring break television special, hosted by Swerve (BRET HARRISON), along with Pixie (KRISTA KALMUS), who is a star of "Sherman Oaks: The Real Valley." Meanwhile, on the West Coast, Carter (recurring guest star BILLY CAMPBELL) packs his bags and leaves Kirsten alone at the offices of Newport Living, and Trey (recurring guest star LOGAN MARSHALL-GREEN) misinterprets Marissa's friendship. Also, rapper T.I. (himself) performs his hit single "Bring Em Out".

Since Carter's departure, Kirsten has been drinking more than just tomato juice for breakfast, and when Sandy questions her, he's left to sleep alone in the bedroom. Marissa's nervousness around Ryan leads him to wonder if something has happened between her and Trey (recurring guest star LOGAN MARSHALL-GREEN). Summer, tired of Seth and Zach (recurring guest star MICHAEL CASSIDY) behaving foolishly, confronts Reed (recurring guest star MARGUERITE MOREAU) about the graphic novel and finds herself center stage at the Atomic County launch party. Meanwhile, Caleb shows Julie that a picture is worth a thousand words.

Sandy and Caleb confront Kirsten about her behavior. Ryan heads home to Chino, as he looks for the truth about Trey (recurring guest star LOGAN MARSHALL-GREEN) and Marissa. Meanwhile, Summer refuses to let her three-way relationship with Zach (recurring guest star MICHAEL CASSIDY) and Seth stop her from attending the prom. And, Julie and Caleb toast to their final evening together as husband and wife.

In the season finale, Sandy must make a life-changing decision to save his marriage to Kirsten. Seth, Summer, Marissa and Ryan are caught in the crossfire at The Bait Shop; and Jimmy Cooper (former series star TATE DONOVAN), worried about Marissa and his family, rushes home to Newport Beach.

The lives of a group of friends and families have forever been changed by the arrival of an outsider to their affluent ocean-side community of Newport Beach in Orange County, California. When Ryan Atwood (series star BEN McKENZIE) was taken in from the streets of Chino by then public defender Sandy Cohen (series star PETER GALLAGHER), the Cohens had no idea how Ryan's arrival would change their lives and the lives of those around them. Initially resistant, Kirsten Cohen (series star KELLY ROWAN) opened her heart to accept the outsider just as she had accepted Sandy, another outsider, into her powerful old-money Newport Beach family. Their "adorkable" son, Seth (series star ADAM BRODY), found a friend and brother in Ryan to share his quirky way of looking at the world--and the trials and tribulations of winning the heart of Summer Roberts (series star RACHEL BILSON), Seth's lifelong crush.

Chaos reigns in the Cohen kitchen as Sandy, Ryan and Seth continue to cope with Kirsten's rehab. When Sandy encourages Kirsten to come home to her family, Kirsten's attachment to Charlotte (recurring guest star JERI RYAN) raises concern in Sandy. Meanwhile, at The Harbor School, Dean Hess (recurring guest star ERIC MABIUS - "Eyes"), the new Dean of Discipline, arrives and makes a decision that changes Marissa's life forever. Summer trumps her cardigan-wearing, goody two-shoes nemesis Taylor Townsend (recurring guest star AUTUMN REESER) when planning the annual Kick-Off Carnival. And Jimmy (recurring guest star TATE DONOVAN) offers Julie a surprising proposal.

Although they are finally happy with each other, Marissa and Ryan are forced to stay apart by their parents, Julie and Sandy. Dean Hess (recurring guest star ERIC MABIUS) pressures Seth and Summer into showing Harbor school spirit, which leads them to devise a covert plan to bring Marissa and Ryan together. When the scheme works, Marissa and Ryan have a night to remember, and Seth and Summer get caught by Taylor (recurring guest star AUTUMN REESER). Meanwhile, Caleb's will is read, leaving Julie stunned and Jimmy in dire straits.

Marissa adjusts to life in her new surroundings and makes some new friends at Newport Union, while Ryan wonders how their separation will affect their relationship. Seth's feud with Dean Hess (recurring guest star ERIC MABIUS) lands Summer in trouble, but some startling new information about Taylor (recurring guest star AUTUMN REESER) may turn the tables once more. Kirsten's friend Charlotte (recurring guest star JERI RYAN) lands in Newport with some big ideas, while Sandy mulls over the future of the Newport Group. Meanwhile, Julie may no longer be a Newport Beach socialite.

Ryan makes a life-changing decision that Sandy surprisingly supports, and Marissa turns to her new public school friends for help with Ryan. The Harbor School's Dean of Discipline, Dean Hess (recurring guest star ERIC MABIUS), continues his crusade to ruin Ryan's future, and Summer and Seth go on their own crusade to reveal Dean Hess's secret. Meanwhile, Charlotte (recurring guest star JERI RYAN) makes Julie an offer she cannot refuse.

Taylor (recurring guest star AUTUMN REESER) ruins Seth's night when she throws a Harbor School event that keeps Summer at a distance. Marissa's new friendships at public school worry Summer, and she enlists Ryan's help. Meanwhile, Sandy works on a plan for the Newport Group and forms a new partnership. And Charlotte (recurring guest star JERI RYAN) convinces Julie and Kirsten to edge back into Newport society.

When the gang heads to The Bait Shop to see the British rock band THE SUBWAYS (themselves), Taylor's behavior causes a major rift between Seth and Summer. Determined to end the potentially explosive conflict between Ryan and Kevin Volchok (recurring guest star CAM GIGANDET), Marissa watches out for Ryan. Meanwhile, Matt (recurring guest star JEFF HEPHNER), Sandy's Newport Group partner, goes above and beyond the call of duty. Julie reigns supreme as the only bitch in Orange County, and for once, Ryan must control his anger.

As seniors at Harbor School and Newport Union prepare their college applications, Ryan, Seth, Summer and Marissa decide what to do about their futures. Will they go to college? Unable to make a decision, Marissa attends Johnny's (recurring guest star RYAN DONOWHO) surf competition instead of completing her college application. Meanwhile, Julie is forced to return to her roots, and Kirsten, eager to get back to work, asks a friend for help. Sandy invites an old friend from UC Berkeley to dinner with Seth and Ryan. Alternative rockers THE SUBWAYS perform. Former series star TATE DONOVAN makes his directorial debut.

Ryan takes an internship working for Sandy and Matt (recurring guest star JEFF HEPHNER) at the Newport Group, but he ends up working harder to save Matt's reputation. Determined to get accepted to Brown University, Summer and Seth do whatever it takes to stand out at Harbor School. Johnny (recurring guest star RYAN DONOWHO) finally tells Marissa how he really feels about her. After a stressful weekend, Ryan and Marissa cross paths and end up telling each other the truth about their time apart.

After the teens spend hours picking out the perfect Christmas trees, they devise a special plan to help a friend in need. Meanwhile, missing her mom, Summer feels even more somber during this holiday, and Johnny's (recurring guest star RYAN DONOWHO) sudden misfortune forces him to take matters into his own hands. Kirsten tries to put the past behind her and make amends with Julie. Reminiscing Seth vows to put a little "mukkah" into Ryan's "chris," and Ryan gets "Bar Mitz-vahkkahed" on the third annual Chrismukkah episode.

Summer, Seth and Ryan launch a campaign to get Marissa back into The Harbor School, and Johnny (recurring guest star RYAN DONOWHO) struggles between a friend's happiness and his own feelings. Meanwhile, Sandy must make an ethical decision that could change Marissa's fate, and Summer's father, Dr. Neil Roberts (recurring guest star MICHAEL NOURI), and Julie are apprehensive about admitting to the lies they have told their daughters.

Fourteen-year-old Kaitlin Cooper (recurring guest star WILLA HOLLAND) returns to Orange County during her winter break from an exclusive Montecito boarding school--bringing a lot of attitude and a few secrets. Much more in the mold of her mother, Julie, than her sister, Marissa, Kaitlin turns heads as she tries to get closer to her family in the only way she knows how.

While Marissa does all she can to get to know her sister again, Kaitlin (recurring guest star WILLA HOLLAND) just stirs up trouble for the gang as she prepares to celebrate her birthday. Meanwhile, Sandy encourages Seth about college, but Seth finds a better alternative. Sandy and Matt (recurring guest star JEFF HEPHNER) work together to secure a contract for the new hospital. And Julie continues her quest to put her family back together.

Summer discovers the truth about Seth. Sandy and Matt (recurring guest star JEFF HEPHNER) encounter an obstacle to their hospital project. Kirsten and Julie take their matchmaking business a little too far, causing Julie to go into hiding. Marissa finally tells Johnny (recurring guest star RYAN DONOWHO) how she truly feels. And Kaitlin (recurring guest star WILLA HOLLAND) wonders which Cooper Johnny really likes.

Tragic news forces the friends to sort out their problems and face the reality of the situation. After Johnny's cousin, Sadie Campbell (recurring guest star NIKKI REED), arrives in Newport, Ryan helps her move and get rid of Volchok (recurring guest star CAM GIGANDET), causing Ryan to question his and Marissa's relationship. Meanwhile, Kaitlin's (recurring guest star WILLA HOLLAND) winter break is over. Just as she gets close to her family, she once again has to say goodbye. And in the wake of Newport's latest events, Kirsten and Julie press on with their Valentine's Day party.

Sadie (recurring guest star NIKKI REED) and Ryan go on a road trip to find one of Johnny's relatives. Although Ryan returns to his old "Chino" ways, the trip brings him and Sadie closer. Could this mean the end of Ryan and Marissa's relationship? Meanwhile, Marissa is implicated in Johnny's death, and Seth and Summer discover Julie and Dr. Roberts' (recurring guest star MICHAEL NOURI) secret. Musician TOM VEK performs.

Ryan struggles with the decision of whether or not to invite Marissa to his birthday party, and Sandy wants to include one of Ryan's relatives in the celebration. Meanwhile, Julie and Dr. Roberts (recurring guest star MICHAEL NOURI) come clean with Summer and Marissa. Also, Ryan and Sadie (recurring guest star NIKKI REED), along with fellow new couple Marissa and Volchok (recurring guest star CAM GIGANDET), grow closer.

When an old nemesis returns to Newport, Ryan gets caught up in helping her, causing a rift between him and Sadie (recurring guest star NIKKI REED). Seth and Summer are faced with a new problem that Taylor (recurring guest star AUTUMN REESER) tries to solve. Meanwhile, Marissa finds herself all alone in Newport with no one to turn to, and Sandy grapples with business pressure.

Julie and Dr. Roberts (recurring guest star MICHAEL NOURI) announce their engagement, and the Cooper ladies move in with Summer and her dad. Meanwhile, Marissa drifts away from Summer and the group when she seeks solace in the company of bad boy Volchok (recurring guest star CAM GIGANDET) and his crew. Ryan tries to move on with Sadie (recurring guest star NIKKI REED), but Seth's concern for Marissa gets in the way. At the Newport Group, Sandy's woes with Matt (recurring guest star JEFF HEPHNER) continue. And Kirsten surprises Seth with a night out.

The kids receive their college acceptance and rejection letters, forcing them to make some life-altering decisions. Ryan and Sadie (recurring guest star NIKKI REED) try to decide what do after high school, and their decision concerns Sandy and Kirsten. Taylor (recurring guest star AUTUMN REESER) throws a college sweatshirt party at Harbor High School, and Marissa and Summer patch up their friendship. Meanwhile, the drama surrounding Sandy's job intensifies and starts to affect the Cohen household.

Ryan leaves Newport to visit his mom, but before they meet, he has a steamy encounter with her co-worker. Meanwhile, Seth is keeping secrets, and Taylor (recurring guest star AUTUMN REESER) and Summer devise a foolproof plan to figure out what's going on with him. When their plan backfires, Summer is devastated. Julie Cooper visits a surprised Volchok (recurring guest star CAM GIGANDET) and gives him some stern advice. Later, Marissa confronts Volchok's friends and saves a girl from an intense situation at a raging party. Meanwhile, Sandy puts an end to the trouble with Matt (recurring guest star JEFF HEPHNER) but leaves Kirsten at home alone.

With graduation just weeks away, Ryan, Seth, Summer and Marissa leave Newport to attend their respective pre-freshman orientations at Berkeley and Brown. While dropping the boys off at the airport, Kirsten is surprised to see Theresa (recurring guest star NAVI RAWAT) and her familiar-looking baby boy. At Brown, Seth runs into Anna (recurring guest star SAMAIRE ARMSTRONG), and they instantly connect. Meanwhile, Kirsten and Sandy attend a hospital benefit where Kirsten vents her frustration and falls back into an old habit.

Harbor School's senior prom brings out the best and the worst in everyone. Taylor (recurring guest star AUTUMN REESER) has a great time, while Summer doesn't enjoy herself with her surprising prom date. Seth and Anna (recurring guest star SAMAIRE ARMSTRONG) come up with a plan to win Summer back for Seth. Meanwhile, Marissa convinces Volchok (recurring guest star CAM GIGANDET) to go to the prom with her, and Ryan brings an unexpected old flame. When one of the girls is elected prom queen, it truly becomes a night to remember. Later, when Taylor's prom funds are discovered to be missing, Ryan returns to his old ways, and prom night turns brutal. LISA TUCKER ("American Idol") guest stars as herself.

Dealing with the repercussions from prom night, Ryan must make a deal with Volchok (recurring guest star CAM GIGANDET). Meanwhile, although Sandy is named Man of the Year by a magazine, the district attorney continues to investigate his unique involvement with the new hospital. After she receives a call for help from Kaitlin (recurring guest star WILLA HOLLAND), Marissa visits her little sister at boarding school. Ryan's bloodied hands force Theresa (recurring guest star NAVI RAWAT) to make a difficult decision. And Seth's actions ignite even more trouble in Newport.

The end of senior year is finally here, bringing the excitement of graduation and the anticipation of new lives in college and beyond. But for Seth, Ryan, Marissa and Summer, it's also a time to look back on the amazing journey that has brought the four of them this far. Seth must confront his recent misdeeds or deal with the wrath of Sandy--and the police. Ryan's proud mom arrives with a surprise for him. Marissa receives an astounding proposal that may radically change her plans. And Summer, facing the prospect of going away without Seth, can't stop crying and hugging her best friends as they say their farewells. Kaitlin (recurring guest star WILLA HOLLAND) returns and moves into Julie's home, vowing to become the next Cooper to rule Harbor High. And to Taylor's (recurring guest star AUTUMN REESER) joy, the "core four" turns into the "fab five." However, although the kids may be ready to move on to bright futures, unresolved issues from their past could ruin everything.

Everyone struggles to adjust to life without Marissa. Dealing with her death in the only way he knows how, Ryan has moved out of the Cohen house.

Ryan travels to Mexico, with a stubborn Seth in tow, to put an end to his turmoil in the only way he knows how, but he comes up short in his quest for revenge.

Sandy makes a deal to help Volchok but lets Ryan intervene and finally settle the score. Meanwhile, Julie opts to spend most of Thanksgiving alone.

When Summer tries to become the gossip-loving girl she once was, she realises that Brown may have changed her forever.

Summer and Che take their activism to a new level, resulting in more freedom than they expected. Meanwhile, Julie flirts with a hot tennis instructor whom Kaitlin likes.

When Seth visits Summer at Brown, he finds an empty dorm room. Meanwhile, Sandy and Kirsten take advantage of an opportunity to bond with Ryan, who is in a Taylor-induced haze.

After Ryan and Taylor have an accident while hanging holiday lights, they realise that everything is not as it seems, and they must do whatever it takes to make things right again.

Ryan plans a special surprise road trip for Taylor and himself. But when Summer confronts Seth about not making any plans, Ryan's romantic getaway for two is spoiled.

Newly engaged Seth and Summer both panic about the prospect of marriage, but neither will break it off, despite the advice of their friends.

Taylor's ex-husband, Henri-Michel, gets a little too close to home while promoting his erotic memoirs, causing Ryan to question his own relationship with Taylor.

Che dreams that he might be in love with someone unexpected. Seth and Summer speak to each other and Taylor decides that she doesn't want Ryan in her life anymore.

On her 40th birthday, Kirsten gets some news that will change her life forever. Meanwhile, Julie is having a secret love affair while Kaitlin does everything she can to stop it.

Ryan worries that the pressure of Valentine's Day will ruin his relationship with Taylor. Meanwhile, a psychic's predictions cause Summer and Seth to question their relationship.

Summer helps Taylor come up with a plan to help Ryan express his feelings. Kaitlin misbehaves outrageously in reaction to Julie dating Frank and an earthquake shakes Newport Beach.

After the earthquake, Seth takes over when Ryan is injured, Sandy takes charge of a crowd in a damaged shopping mall and Taylor is reunited with someone from her past.

Ryan, the Cohens, the Coopers and their friends build new lives, resolve lingering issues, face major decisions and undergo shocking personal transformations.