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.

As Silver's "half birthday" approaches, she decides to spend a spooky evening by watching horror movies with her friends at the famous Hollywood Forever Cemetery. But Dixon is not eager to attend when he reveals to her that he does not watch horror films. Meanwhile, Harry's past returns to haunt him when Tracy reveals she is searching for their long-lost illegitimate son. Annie and Ethan are paired up for an assignment, which leads to a possible romantic connection after the two take care of a baby. A mysterious new student, named Kimberly MacIntyre, arrives at West Beverly which considers with a police raid on the school searching for narcotics which leads Naomi to cover for Adrianna when Naomi takes the fall by taking her cocaine stash. After Naomi confronts Adrianna over her escalating drug addiction, she agrees to come forward to clear Naomi, but Adrianna soon goes back on her word when she lands another acting role which could jump-start her acting career and make her difficult-to-please mother proud. Also, Ryan seeks to explore his horizons since his breakup with Kelly by dating an attractive, but dim-witted actress.

After spending several days in the hospital recovering from a near-fatal drug overdose, Adrianna tries to make amends with Naomi. But Naomi refuses to forgive Adrianna for her betrayal. While serving her detention, Naomi meets a trouble-making punk, named Ozzie, who could spell trouble for her. Later, Adrianna makes a connection with Navid, who helps her through her situation as she's accepted into a rehab clinic. Meanwhile, Annie and Ethan finally take their rapidly growing romance to a new level during the school's annual homecoming dance, causing Naomi to feel jealous. Dixon asks Silver to the dance, but she turns him down for she feels, in her liberal and radical mind, that Homcomming is the scene of the morally corrupt. Ryan believes that the new student, Kimberly, is a narc after he sees her purchasing drugs. Also, Debbie confronts Tracy about the time Tracy kissed Harry.

Silver invites a few of her female friends over at her house for a girls' night, but the event quickly turns into a house party which causes massive damage to hers and Kelly's house. Meanwhile, Debbie and Harry finally reveal to Dixon and Annie that they have a long-lost, out-of-wedlock brother who was given up for adoption by Tracy Clark over 20 years ago. Dixon, who does not appear upset by the news, deals with the situation by talking to Silver about it. However, the news bothers Annie and she takes out her anger and frustration at Silver's party by getting drunk and being insulting to everyone. Annie and Ethan decide to keep their relationship a secret, while Naomi continues to hang out with the trouble-making Ozzie. Elsewhere, Adrianna and Navid continue to grow close until they have a misunderstanding. Also, a student sees Ryan and Kimberly kissing and begins to make demands to Ryan, while Kimberly is just determined to keep her secret identity under wraps at any cost and informs Harry about what's transpired between them.

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.

Adrianna reveals the secret that she's pregnant individually to both Naomi and Navid, who handle the news differently than expected. When Dixon reveals the depths of his feelings to Silver, their relationship takes a surprising turn when she reveals some facts about herself and that of her feelings of love. Meanwhile, Tabitha surprises Annie and Dixon with an unexpected belated Christmas gift of a car: which both Debbie and Harry disapprove of Tabitha trying to buy her grandchildren's affection after she also announces that she is leaving town to re-start her acting career with a job on a TV soap opera in New York. With a massive heat wave hitting the L.A. area, Annie and Ethan decide to to take a day-long escape to Tabitha's house Palm Springs for a romantic time alone.

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.

Christina invites Dixon and Navid and the rest of the students to a house party where the band Carolina Liar will perform and Navid moves on from his relationship with Adrianna by connecting with a fellow Iranian girl named Nika. Meanwhile, Ethan gets involved in a traffic accident with a girl named Rhonda Kimble, a student at West Beverly whom he feels guilty about not knowing her since she's a long-time student. Adrianna and Naomi try to debate about how to tell both her mother Constance, as well as Ty, about Adrianna's pregnancy. While Ty takes the news very calmly, Adrianna fears a violent reaction from her selfish mother whom relies and takes advantage of Adrianna's acting career. But Adrianna finds out that Ty's parents want to bribe her to get an abortion and keep the news a secret. Eventually, Adrianna broadcasts a video announcement of her pregnancy to the entire school.

As Valentine's Day approaches, Adrianna's pregnancy now becomes the talk of the entire school as her 'baby bump' begins to show, while Navid continues to ignore her and grows more closer to Nika. Meanwhile, Silver asks Naomi for help in planning to make the best Valentine's Day ever for Dixon by setting up a dinner at the hotel where Naomi is now living at. But later, Dixon freaks out when Silver gets a much too permanent tattoo of their love to try to bring them back together. Also, Ethan's friendship with Rhonda continues to blossom which makes Annie very jealous, while she begins taking acting workshop lessons and tries to find her own motivation. But Rhonda begins using her medical condition to manipulate Ryan's too-trusting kindness to lead him more closer to her. Elsewhere, Naomi meets Liam Court, a bartender at the hotel in which they click romantically at once, but suspicion plagues Naomi as to whom Liam is when he does not want to talk about his personal life.

When Liam transfers to West Beverly, Naomi finds herself stunned but captivated by the intense, handsome bad-boy who takes her out on weeknights to partake in illegal street racing. Meanwhile, Annie drifts further apart from Ethan and spends an evening under the stars with fellow thespian Max. Annie also begins to suspect that Rhonda is not who she appears to be and also correctly suspects Rhonda of using her medical condition to play on Ryan's sympathies. Eventually, Ethan tells Rhonda that he's not interested in a relationship with her, but he breaks up with Annie over their differences. Elsewhere, Dixon begins to question his relationship with Silver, as well as her mental capacity when she makes a sex tape of them and shows it at part of her film project for Ryan's class. But it takes a turn when Silver finally reveals her dangerously disturbed personality when she breaks into Ryan's apartment and threatens him with physical harm.

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.

Navid and Adrianna fantasize about their future, but when they tell his parents about their decision to spend the rest of their lives together, things don't go as they planned when both Mr. and Mrs. Shirazi threaten to sever all ties to their son. Meanwhile, Silver tries to adjust to her new Catholic girls school, but soon learns that it is not all it's cracked up to be when her new school mate, Angela, gives her some advice to be honest about her past. Silver goes along with it... and later regrets it. While Dixon feels left out of Silver's life, Annie and the rest of the Wilsons are dealing with having Naomi as their new house guest. Naomi convinces Annie to go on a double date with Liam's friend, but Annie is shocked at the way the evening ends when Liam propositions to her. Later, Naomi's older sister Jen, who's just as brash and amoral as she, arrives in town for a visit. Naomi has no idea just how devious her sister is... and of her connections to Ryan as well as Ethan.

Following their engagement, Navid and Adrianna celebrate their respective bachelor and bachelorette parties. While Adrianna feasts with Annie, Naomi, Silver, and their female friends at the Wilson home, Liam takes Navid, Ethan, and Dixon to have a wild night on the town with some college girls at a burlesque club. Meanwhile, sparks fly between Ryan and Jen, and Dixon continues to feel unappreciated by Silver. Jen also persuades Naomi to stand up to their father as well as move in with her at a local house, while Naomi continues to grow more insecure as well as jealous over Liam when she sees him talking with Annie whom he sees as naive and holding back her own dark side.

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.