90210 revolves around several students at the fictional West Beverly Hills High School, including new Beverly Hills residents Annie Wilson and Dixon Wilson. Their father, Harry Wilson, has returned from Kansas to his Beverly Hills childhood home with his family to care for his mother, former television and theater actress Tabitha Wilson, who has a drinking problem and clashes with his wife Debbie Wilson. Annie and Dixon struggle to adjust to their new lives while making friends and yet adhering to their parents' wishes.
In the season five premiere, Naomi and Max make some big plans that go horribly awry when they both get arrested and land in jail. Liam is forced to put The Offshore up for sale in order to pay off Vanessa and buy out her $200,000 interest in Liam’s movie contract. Navid approaches Liam about becoming his business partner. Teddy is overwhelmed by Silver’s request to father her baby. Adrianna, unaware Dixon has gotten into a life-threatening accident, has an unforgettable evening in Las Vegas with a handsome stranger, Taylor, after she vows to get over Dixon and move on with her life. Annie asks Ade to return to Los Angeles to be with an unconscious Dixon, and the two girls decide to move into the beach house together.
Naomi and Max’s honeymoon plans are put on hold after Alec informs Max that his whirlwind wedding has caused a public relations problem and lowered their tech company’s stock price. Naomi decides to throw a high-class reception to reassure Max’s investors that their marriage isn’t a cause for concern. Adrianna discovers that club promoter Taylor, her one-night stand from Las Vegas, is partnering with Liam and Navid to re-launch The Offshore. Adrianna insists that their fling was a one-time thing, but Taylor suspects she has deeper feelings. At physical therapy, Annie and Dixon encounter fellow patient, Riley, who warns Annie to stop babying Dixon so he can learn how to manage on his own. At home, Dixon explodes on Annie and tells her that he’s tired of her help. Liam offers to buy out Vanessa’s portion of his movie contract, but Vanessa blackmails Liam to be her boyfriend again by threatening to show the police hidden camera footage of Liam. Silver invites Liam to be her date at Naomi’s reception, but gets a surprising answer. Liam confronts Vanessa after the reception, but their argument is cut short by a shocking accident.
Silver has yet to schedule her insemination appointment, and worries that she’ll no longer be attractive after undergoing the preventive surgeries. Adrianna encourages Silver to treat herself to an irresponsible day of fun doing all the things that she won’t be able to do once she becomes a mother. Alec ignores Naomi’s gestures to make nice, so Naomi poses as a wealthy investor and lures him to her yacht for a phony business meeting. The two reach an agreement to get along, and Alec spontaneously kisses Naomi, which she rebuffs. Alec apologizes, but Naomi insists on telling Max, unaware that Alec had planted the kiss to blackmail her. Meanwhile, Annie thinks that Riley is too hard on Dixon, but Riley insists that Dixon needs to change his attitude in order to accelerate his recovery. Liam learns that his video game contract can’t be finalized without Vanessa’s approval, so Annie encourages him to speak with her attorney, Lindsey Beckwith. Liam worries when a detective shows up asking questions about Vanessa’s whereabouts.
Naomi plans a romantic getaway with Max, intending to disclose that Alec kissed her, but when Max persuades Naomi to perform a trust-building exercise, she freaks out when she’s unable to complete it. Silver discovers that nude pictures from her photo shoot have been posted on the internet, and receives help removing them from Annie’s new prospect, Collin. Liam enrolls in Lindsey's business law class, but she assumes he’s not serious about his education. Liam’s new costar, Kendall, is harassing him to begin a relationship with her for publicity, so Liam attempts to escape by going camping with Navid and Dixon. When Liam goes missing in the woods, Kendall seizes the opportunity to alert the media to find him. Meanwhile, Dixon encourages Adrianna to hire Taylor to create her new music video concept. After Taylor dares Adrianna to show him how sexy she can be, she realizes that she has feeling for him.
As Dixon continues to recuperate, Adrianna confides in Annie that she and Dixon are having intimacy issues. Annie grows closer to Colin, but Riley suspects that Colin isn’t who he appears to be. Colin discovers that Alex installed a GPS tracking app on Naomi’s phone so he can track her whereabouts, but Colin reconfigures her phone so she can secretly read Alec’s emails, which exposes Alec’s efforts to sabotage Max’s relationships. Navid hopes to show Silver how successful he’s become with the launch of the Pop Up, but he becomes suspicious that Silver and Liam are secretly seeing each other. Lindsey comes to the opening event to discuss Liam’s business plan, and their animosity gives way to passion.
Liam and Lindsey keep their relationship under wraps, but when Navid's jealous streak gets the best of him, he arranges for Liam and Lindsey's sex tape to be shown in place of Liam's movie premiere at Phenomi-com. Riley admits his feelings to Annie, but Annie's more interested in giving her relationship with Colin a chance. Meanwhile, Max tries to figure out how his company's video game technology got hacked, so Naomi and Alec work together to demo a new video game at Phenomi-con. Taylor feels guilty for hooking up with Adrianna, so he tells her to end things with Dixon if she wants to be with him. Dixon collapses due to a spinal infection, and Adrianna learns that he stopped taking his pain medication because he was afraid to become addicted again.
When Adrianna opens at the Hollywood Bowl for a headlining artist, Dixon decides to buy her a celebration gift. Suspecting he might propose, Silver convinces Ade to come clean about her affair with Taylor. Annie confronts Riley about standing her up for wrongly suspecting that Annie is uncomfortable with his disability. Naomi encourages Max to hire an executive to replace Alec, but she’s uncomfortable when the perfect candidate-on-paper turns out to be a gorgeous girl, Bryce Albright. Liam receives a threatening letter that suggests the anonymous source knows the truth about Vanessa’s disappearance, and he’s relived when off-duty L.A.P.D. officer, Ashley Howard, becomes his bodyguard.
Naomi hosts an elaborate charity lingerie show at the Playboy Mansion in an attempt to gain membership status with the elite ladies West Beverly alumni group. Silver surprises her West Beverly High friends by performing burlesque at this stylish Homecoming event. Liam confides in Annie about Vanessa’s accident and tells Annie about the blackmail threats he’s received. Liam also accepts Navid’s apology for leaking Liam’s sex tape and offers Navid the chance to manage The Offshore. While Dixon is making big plans for Adrianna’s career on his new record label, he discovers that Ade had other desires aside from music.
When Alex approaches Max about forming a new company with him, Naomi intervenes by attempting to persuade Bryce to rehire Max at his company. Naomi convinces Navid to take Bryce out for drinks, and after a few cocktails Navid uncovers the truth about Max's termination, which leaves Naomi pondering the fate of her marriage. Then, Liam receives a blackmail letter about Vanessa's accident, and Annie agrees to lend him the money to help trap his blackmailer. But when Adrianna tells Ashley that she spotted Vanessa at the beauty salon, Ashley wrongly suspects that Liam was headed for a secret rendez-vous with Vanessa. Meanwhile, Silver is distraught when Teddy refuses to sign over his parental rights and tries to convince her to let him co-parent the baby.
Annie and Vanessa search for Liam after discovering that Ashley was falsely posing as his studio-hired bodyguard. Needing a break, Naomi goes on a road trip with Adrianna, only to have her wedding ring stolen. Meanwhile, Dixon fails to convince Megan he is over Adrianna.
Annie experiences an alternate reality about what life would have been like if she had stayed in Kansas, including being engaged to her high school boyfriend. In the alternate world, Dixon becomes a massively successful hip hop artist who no longer has contact with his family, while Adrianna is a washed-up actress and Hollywood’s bad girl. Naomi is a real estate agent, and Teddy has not revealed his true sexual orientation.
Naomi and Max see a marriage counselor to decide if they are going to stay married, while Teddy tells Silver he won’t ruin her chance to have a baby if she agrees to his terms. Navid uses Liam’s celebrity status to help him get into an elite secret society and Annie rushes to tell Riley her true feelings before he undergoes an experimental surgery.
Naomi and Max co-host a charity football game which re-kindles old feelings, while Navid pushes Liam to continue underground fighting. Adrianna purposely sabotages a performance so Dixon will let her out of her contract, and Annie’s blog gets the attention of a publisher.
Liam experiences some symptoms of post-traumatic stress disorder while preparing to testify against Ashley, while Annie is furious when Naomi tracks down their half-brother Mark, a chef who owns a gourmet food truck. Silver is overbearing with her surrogate Michaela, whom Dixon discovers has an amazing singing voice.
Naomi decides to open a restaurant with her half-brother Mark, while Dixon books Michaela to perform at the restaurant opening, unbeknownst to Silver. Annie feels confused about her newly re-surfaced feelings for Liam and Navid agrees to escort Campbell’s fiancé to an event, only to find out Campbell is cheating on her.
Liam decides to open his own custom surfboard shop for women, but things get complicated when he becomes romantically involved with his first investor. Naomi tries to convince Mark to stay in Los Angeles after he receives an offer to be head chef at a restaurant in New York, while Dixon convinces Silver to direct Michaela’s first music video before she gets pregnant.
Naomi meets up-and-coming mogul Jordan Welland, who hires her to plan events for his media empire, while Annie, Adrianna and Silver plan a girls’ night out for Naomi, which ends with disastrous results. Dixon starts to develop feelings for Michaela, and Liam finds out that the Cronus brothers plan to blame Navid for the cheating ring and is forced to befriend them to clear Navid’s name.
Jordan asks Naomi to plan a launch party for the latest hot writer, known as Author X, which forces Annie to admit that she is Author X. Silver worries that Adrianna is not okay that she is dating Mark. Meanwhile, Dixon finds out that Michaela has feelings for Navid.
Liam and Navid, in an effort to get teenage pro-surfer Cassie to be their first sponsored athlete, ask her favorite musician Olly Murs to do a special performance. Naomi travels to New York to make a good impression on Jordan’s mother, Cheryl with disastrous consequences. Annie decides to publicly say her novel is fiction but Dixon persuades her to tell the truth.
Jordan calls in a favor from his mother to help out Mark, but in exchange must end things with Naomi. Annie must deal with the betrayal Liam feels from being in her book and Michaela catches Navid and Adrianna during an intimate moment.
Jordan's sister Elizabeth gets into trouble with an out-of-control Royal, so Naomi helps out by taking the heat to protect Elizabeth's reputation. Silver is called in to see her doctor about some test results and Annie decides to get over Liam by going to Paris for a book tour. Meanwhile, Adrianna performs after Fall Out Boy at a big event, but the concert ends in chaos.
In a memorable send-off, our favorite group from Beverly Hills will come together again after a traumatic event that makes them realize the importance of their relationships.