The Wilson family arrives in Beverly Hills, after Harrison "Harry" Wilson takes a job as the principal at West Beverly High School, while his children, Annie and Dixon, attend the school during their first week much to the awkward circumstances of their father watching over them, while Harry and his photographer wife, Debbie, also keep a close eye on Harry's washed-up, alcoholic, actress mother, Tabitha. For Annie and Dixon, the school is one big culture shock for Annie, a sweet and friendly girl with a passion for the theater, and Dixon, a star athlete and scholar who was adopted by the Wilson family after they took him in as a foster child. Annie and Dixon have a close sibling relationship, which they'll need to help them cope with all the new cliques and classmates, including Naomi Clark, a hot and stereotypical spoiled rich girl who believes that money buys everything; Ethan Ward, Annie's former boyfriend from Kansas who's now Naomi's boyfriend, and a popular lacrosse star whose abilities rival Dixon's; Navid Shirazi, an aspiring student reporter who heads up the school's daily TV newscast; and Erin Silver, a rebel and wanna-be socialite who produces and stars in a YouTube-type video series, and who develops a crush on Dixon. Adrianna is a fellow student and theater "goddess" who is Naomi Clark's best friend... and Ethan Ward's secret girlfriend, and who has a serious drug addiction; George Evans is an arrogant West Beverly High student, who takes an instant dislike to Dixon because of his race (Dixon is black). Wendy is "sexy vixen" student at West Beverly Hills High who takes every advantage of her looks; Ty Collins is another student and theater major. Even the faculty seems hip and sophisticated at the school whom include the smart and funny teacher Ryan Matthews, beautiful guidance counselor Kelly Taylor, and successful theater actress-turned-high school-musical director Brenda Walsh. The Wilson family has just begun to realize how much their lives are about to change.

Naomi finds herself in trouble when she fails an assignment, and Ryan and Kelly bring the issue to Harry's attention, while Harry struggles with a disturbing revelation about the result of a secret tryst with Naomi's mother, Tracy, from many years ago. Meanwhile, Dixon learns more about Navid when they team up to try to pull a school prank against Palisades High. Annie meets a potential love interest in the form of drama student Ty Collins, who turns out to be the wealthiest student at West Beverly, and who spirits her away for San Francisco for the evening. Silver posts the story about Ethan's infidelity with Naomi on her Internet blog, while Adrianna continues her self-destructive slide into drugs and debauchery. Also, Ryan tries to ask Kelly out on a date, but she has to find a babysitter first for her four-year-old son, and former West Beverly alumni Brenda Walsh, now a successful Broadway and London theater director, arrives back in town to help put on a new school play.

Dixon and Annie find their Friday night plans disrupted after Debbie and Harry plan a family bowling night without consulting them. So, Annie plans to sneak out of the place to meet with Ty to attend a rock concert, while Dixon plans with Navid and Ethan to sneak him out so they can watch a movie at Navid's house. Meanwhile, Naomi has an unpleasant evening with her estranged and selfish businessman father, Charles, who puts her off for work. Also, Dixon invites Silver over to the Lucky Strike Bowling Alley, and he later finds Silver asleep in his car. Silver then confides in Dixon about her troubled home life and how her drunkard mother, Jackie, verbally and physically abuses her. The news gets back to Kelly who confronts Jackie about it, while at the same time, Kelly continues to be sought after by Ryan who tries asking her out on a date.

Annie and her parents, Harry and Debbie, are surprised to learn that West Beverly's theater director can no longer oversee the school musical. Tabitha offers to direct the musical play, but her eccentric and demanding attitude does not sit well with Annie or the other actresses. Kelly persuades Brenda to take over as the play's director, much to Tabitha's chagrin. But Kelly and Brenda end up continuing to argue over Kelly's continuing involvement with Ryan and taking up time with Kelly's son, Sammy. Meanwhile, Dixon tries to get a part time job at the Peach Pit coffee shop to get money to pay off a bully after Dixon accidentally dents the bully's car. Naomi becomes more distraught over her parents, Tracy and Charlie's, open-marriage arrangement, and she eventually confronts her father's mistress to show her true anger towards her. Elsewhere, Annie's growing relationship with Ty is the talk of the school, which leads to Ethan, who's growing more uncomfortable and jealous, to try to get her attention.

As opening night for the school play nears, Harry catches Annie kissing Ty, which makes him worry that she and Ty are moving too fast with their growing romance. Silver, stressed out from her job as the stage manager, gets some comfort from Dixon. Meanwhile, Naomi tries make her mother and father get back together, but Tracy's mind to divorce Charlie is made up. On the opening night of the play, the star Adrianna's drug use comes to surface from being under constant pressure from her overbearing mother, Constance, and when Brenda discovers this, she replaces Adrianna with Annie in the lead alongside Ty. But when both Brenda and Kelly confide in Constance about her daughter's drug abuse, Constance (a secret drug abuser-in-denial herself) refuses to believe them. Afterwards, Adrianna successfully gets her revenge when she manipulates and breaks up Ty and Annie's romantic get-together at a celebration party at a local hotel.

Adrianna and her evil-witch-mother, Constance, plot a cruel revenge against Annie and the rest of the faculty at West Beverly whom they think cheated Adrianna out of her role in the school play. Debbie's boss, Antonio, offers her a job to shoot a fashion show for Nylon Magazine during Fashion Week, where Annie uses the opportunity to her advantage for a class assignment, while her father advices her to try to make amends meet with Adrianna in order to try to catch her in the act with her substance abuse. Naomi believes the upcoming fashion show could help her parents' marital problems and she plans with Ethan to try to break up her father and mistress and have her mother, Tracy, meet with Charles, but it only makes matters worse. Ty and Annie's relationship is put to the test because of Adrianna's meddling. But when Adrianna lets her guard down and reveals to Annie that she lied about hooking up with Ty to break them up, it results in Annie declaring war. Silver is pursued by Debbie's sleazy client, Tony, to work in modeling, while a jealous Dixon becomes aware about what's going on, while Navid feels like he's the 'third wheel' to Dixon and Silver's growing romance. Meanwhile, Kelly receives a phone call from Sammy's father that could change her relationship with Ryan when she's offered to move to Wyoming to join Dylan, while Brenda, with her work at West Beverly finished, plans to return to New York.

Kelly arrives back in Beverly Hills and reveals to Silver what happened between her and Dylan during her trip. She also confronts Ryan, who has taken a leave of absence, about the rumors that he hooked up with a student, while Ryan refuses to explain his actions to Kelly or anyone else as not to jeopardize Kimberly's undercover status to nail the drug pushers at West Beverly. On Annie's 16th birthday, Naomi sees her kissing Ethan and decides to get back at her by inviting Annie's old boyfriend, Jason, to her birthday party hoping it will break up her and Ethan, who continue to debate over keeping their blossoming romance a secret... unaware that everyone around them already knows. Meanwhile, Adrianna has dinner with Navid and his large Iranian family and she also finds out that Navid is a virgin. At the end, the big twist comes when Harry's 22-year-old illegitimate son, Sean, visits the Wilson family for the first time during Annie's party.

Harry and Debbie welcome Sean into their home, while Dixon, Annie, and Tabatha welcome him awkwardly despite the fact that they don't know much about him, while Naomi and her mother, Tracy, welcome him to their home as well. Meanwhile, Kelly and Brenda's friendship is slowly fading away and gets wider after Brenda is hospitalized from an accident and confides in Kelly that she seduced Ryan weeks earlier. Naomi decides to hang out with a new group of girls at school despite Ozzie's advice that they want nothing to do with her. Also, Silver feels threatened when a cheerleader, named Christina, shows too much interest in Dixon who shares the same interests he does.

Annie overhears Sean in a suspicious conversation with someone over the phone, which raises her uncertainty about whether Sean really is who he claims to be. Meanwhile, Brenda tries to make amends meet to Kelly after confessing about a tryst she had with the departed Ryan Matthews. But Kelly and Brenda have to team up to accompany Adrianna to a group therapy session for recovering addicts where after she learns that a friend of hers is HIV-positive, Adrianna goes to a clinic to get tested, but receives some other potentially life-changing news. Elsewhere, Christina invites Dixon over at her house for a Gospel gathering where she makes a startling revelation to him which could shake his romance with Silver.

Ryan Matthews returns to his job at West Beverly High which causes a mixed reaction for both Kelly, as well as Silver who finds herself writing a class paper on the book 'Heart of Darkness' to win back his trust after he rejects her from his class. Meanwhile, Annie decides to audition for the school's drama production of 'Antony and Cleopatra' and sets her sights on the lead, while she asks Ethan to audition for a role in the play so they can be closer together, while Annie also has a run-in with her one-time boyfriend Ty Collins. Adrianna becomes more uncertain about her pregnancy and refuses to deal with the problem. When her mother goes missing, Naomi is asked by her father, Charles, to move in with him and his mistress at their Malibu beach house which makes the situation very awkward and uncomfortable for everyone. Elsewhere, Silver and Dixon continue to experience bumps in their relationship which leads him to decide if he wants to end his romance with her.

Silver's struggles escalate and she reaches her breaking point. Kelly teams up with Ryan to look for her. Annie is forced to team up with Ethan and Naomi to search the school for Silver while Dixon is haunted by the problems of his past.

Donna Martin returns to Beverly Hills and pays a visit to her sister-in-law Kelly to talk about her life, while Kelly's relationship with her half-sister, Erin, becomes more strained over Kelly's over-protectiveness in her efforts for Erin Silver's mental recovery. Meanwhile, Dixon locates his biological mother and ask Annie's help to travel with him to Arizona to meet with her during Spring Break. Also, Naomi's infatuation with Liam intensifies when she goes on field trip with the class on Ryan's Habitat for Humanity house-building project while Ethan, wanting a change, becomes more acquainted with Liam who encourages him to embrace his own dark side.

Donna finds herself in a dilemma when she confides in Kelly during a night on the town that she must decide between returning to Japan and being with David, or moving back to Beverly Hills and keeping their 20-month-old daughter, Ruby, which leads her to decide to open up her own design shop in Los Angeles. Meanwhile, Silver is the topic of gossip at West Beverly due to her recent mental issues and does not know if she is ready to return to school. While Annie and Naomi try to patch things up between them in order to help Silver, Annie soon overhears that Naomi's father is being served a sexual harassment lawsuit, and she keeps it to herself... and later regrets it when Naomi is evicted from her hotel suite. Ethan continues on his downward spiral due to Liam's bad influence in wanting to be a bad guy as Liam is. Also, Adrianna and Navid meet with potential adoptive parents for the baby. Elsewhere, Harry and Debbie hold a yard sale when they finally sell their Kansas house and try to get rid of all of their old house's possessions as they plan to move out of Tabitha's house and to find a house of their own in Beverly Hills.

As West Beverly prepares itself for the annual prom, Annie, Adrianna, Naomi, and Silver go out shopping together for the right evening gown to wear and try to get all glamored up for the event by visiting a famous hair stylist. A dateless Annie agrees to attend the event with the socially awkward Charlie, who has a massive crush on her. However, when he realizes that Annie is only interested in being friends, Charlie turns against Annie... showing his true repressed psychopath colors to plot a cruel revenge. Naomi attends the prom with Liam while she learns that Jen has emptied out her trust fund to support them living at Jen's new house. Meanwhile, Dixon is nominated for prom king, while Ethan learns that he has been accepted into lacrosse camp for the summer. Also, both Kelly and Harry take action to help Liam get on the right track, while he continues to try to temp Annie to embrace her own dark side as he has with his own. Ryan grows more closer towards Jen, and he also ignores Kelly's warnings that Jen is a devious, sociopath seductress whom is using him for self interest. At the prom, Harry informs the students in attendance that any after-prom activities will be dealt with punishment, while Navid provokes a fistfight with Ty when he reacts with indifference over the pregnant Adrianna's unborn child which is in fact his. When Silver learns that Dixon has nominated himself for prom king, she decides to enter for prom queen as a write-in candidate and finally gets to speak her mind to the attendees.

Adrianna and Navid are forced to make an impromptu exit from the prom when Adrianna goes into labor. Brenda Walsh shows up at the hospital to lend emotional support as Adrianna's labor gets more difficult. Harry and Debbie also turn up at the hospital with Kelly to lend emotional support to Adrianna when she decides to give her baby up for adoption. Across town, in defiance of Harry's orders not to throw any post-prom party, Naomi and Liam decide to throw a party in Jen's house, which she does not approve of. There, Dixon confronts Ethan about Silver when he notices that Ethan might be developing romantic feelings for his girlfriend. When Liam arrives late for the party, Jen takes advantage of his rebellious state. However, Naomi confronts and accuses Annie of seducing her boyfriend. Beaten up and humiliated, Annie leaves the party in a rage. Later, while driving home, Annie runs over someone with her car in a hit-and-run. Liam later decides to confess that it was Jen who seduced him and not Annie. He is unfortunately grabbed by parole officers and sent away by his stepfather to a military academy. Jen is left behind to claim herself as Naomi and everyone's savior... with no one suspecting her true nature.

Teddy continues throwing his charm and weight around by inviting some of the gang to a day-long sailing trip on his father's yacht. There, more relationship troubles hit them. Dixon tries to move on from Silver by inviting over Sasha to whom he lies about his age to impress her. Navid begins to doubt about where his relationship with Adrianna is heading. Adrianna begins to show more appreciation to Teddy, while he continues to rebuff Naomi's further attempts at flirtation. Meanwhile, Annie, broken and humiliated from the nude photo of her that was posted to the entire student body, commits herself on a hell-bent mission to expose Naomi as the perpetrator. Both Harry and Debbie begin to worry about Annie's recent behavior and try to arrange a sit-down of talks with her. However this only stirs up more tension as Annie becomes more bellicose, refusing to talk to anyone. Harry then confides in Kelly about Annie's behavior - Kelly suspects that Annie's hiding something. Elsewhere, Liam is frustrated and disgusted at Annie and Naomi's continuing vicious feud. Neither one of them wants to associate with Liam anymore, so he confines himself to his garage where be begins working on a dark "project".

Both Kelly and Silver deal with the shocking news that their mother, Jackie, is dying of breast cancer. Kelly doesn't want to be sucked back into her mother's bad behavior which continues to persist, but Silver feels differently and wants to re-bond with Jackie. Meanwhile, Navid is devastated when Adrianna tells him that she needs time alone, but she turns to Teddy for attention. Jen continues to manipulate Naomi with her charming personality and manages to convince Naomi to lend her a large amount of cash which Jen plans to use to invest in a race horse. Elsewhere, Jasper rescues Annie from a bad date and the two become fast friends. Also, Harry, seeking to get away from problems at home, accompanies Ryan to a bar for some guy time and attempts to be his wing man when Ryan wants to move on from Jen.

Silver and Kelly continue to argue about caring for their dying mother, in which Kelly wants nothing to do with their drunk of a mother, Silver wants to spend her time caring for her. While dealing with schoolwork and caring after school for Jackie, Silver is paired with Teddy for a class project where they find they have more in common when he tells her that his mother too died from cancer. Meanwhile, Naomi continues her relationship with Richard, but continues to flirt with Jamie. Although coming clean with Sasha, Dixon realizes that he and her are in two different places in their life and decides to break up with her, but she later tells him some "life-changing news". Tensions escalate between between Debbie and Harry when she walks in on Harry and Kelly talking in his office, and Debbie's jealousy and suspicion gets the worst of her. Elsewhere, Annie and Jasper's relationship is put to the test when he attempts to convince her to steal a car while shooting a scene for his student film. Also, Liam butts heads with Ivy, the newest member of the surf team. Most of the gang attend a Halloween costume party at the Beverly Hills Beach Club where Adrianna dresses up as Marilyn Monroe to help her deal with the end of her relationship with Navid.

Kelly continues to support Silver as she deals with Jackie's declining health, despite that she is conflicted about whether or not she can forgiver her mother for the life-long pain and abuse she caused to both her and Silver. Navid confronts Adrianna about her renewed drug use, but this time, she rudely tells him off for turning his back on her. Meanwhile, Harry and Debbie are surprised when Annie informs them she would like to invite Jasper over for dinner at their house. Despite Annie telling Jasper to be on his best behavior, the dinner proceeds very uncomfortably for everyone. Dixon, still alienated and upset with his entire foster family, especially Debbie over her handling of the Sasha situation, declines to join them, and instead teams up that night with Ivy and Navid to set a plan for Liam to tell Naomi the truth about Jen despite knowing that Naomi will not believe them, even with evidence. Elsewhere, Ryan and Jen's relationship is taken to a new level when he convinces her to go on a weekend camping trip. Also, Naomi and Jamie's secret romance is finally found out when Richard and his mother walk in on them in Richard and Jamie's dorm room which finally forces Naomi to come clean about her plans to get accepted into CU.

Naomi returns from her vacation in St. Bart's excited to spend time with Liam. However, their first date is uneventful since they have nothing in common which leads Naomi seducing Liam aboard his his newly built boat. Adrianna and Gia bond after they meet during an AA meeting and establish a support system for each other which leads to the two sharing a kiss at the Beach Club. Meawnhile, Jasper begins to blackmail Annie by threatening to tell the authorities about her hit-and-run accident if she breaks up with him. Navid and Dixon devise a plan to remove Jasper from Annie's life by planting cocaine in his locker, but they never anticipate the outcome of a school drug search. Dixon attempts to rekindle his relationship with Silver, while Silver hides her true feelings for Teddy. Also, Harry and Debbie run into Kelly while attending a school function and the jealous Debbie confronts Kelly about her having a crush on Harry.