Naomi's older sister, Jen, unexpectedly returns to Beverly Hills. Meanwhile, Naomi persuades Annie to go on a double date, and Adrianna and Navid reveal their decision to his parents.

Following their engagement, Navid and Adrianna celebrate their respective bachelor and bachelorette parties. While Adrianna feasts with friends and family at the Wilson home, Navid and the boys spend a wild night with college girls at a burlesque club. Meanwhile, sparks fly between Ryan and Jen, and Dixon continues to feel unappreciated by Silver.

With prom night quickly approaching, Annie, Adrianna, Naomi, and Silver get glammed up by a famous stylist. A dateless Annie agrees to attend the event with the extremely nerdy Charlie, who is massively crushing on the popular girl. But when he realizes that her interest is purely platonic, a furious Charlie plots an evil revenge. Meanwhile, Dixon is nominated for Prom King, Ethan gets accepted into lacrosse camp, and Kelly and Harry work to get Liam on the right track.

Adrianna and Navid are forced to make an impromptu exit from the prom when Adrianna goes into labor. Dixon confronts Ethan about Silver when he notices that Ethan might be developing feelings for his girlfriend. Meanwhile, Annie reaches the breaking point when Naomi accuses her of trying to hook up with Liam, and some of her peers (still angry about the after party fiasco) decide to take both verbal and physical action against her.

Naomi is still furious with Annie from prom night and contemplates sending out a sexually explicit text message of Annie as payback. Silver is convinced that she and Dixon can mend their broken relationship, but Naomi and Adrianna convince her to give him some much-needed space. Liam attempts to apologize to Naomi for what happened on prom night and denies sleeping with Annie, but refuses to reveal who he was with. Meanwhile, Liam and Dixon join the surf team, in an effort to keep Liam's stepfather from sending him off to military school. Adrianna helps Navid, now in charge of The Blaze News, land an interview with Teddy, but she is shocked with Navid's interviewing tactics. Ryan continues to pursue Jen , who continues to play hard-to-get.

Dixon and Sasha continue their whirlwind romance by driving to Napa for the weekend, but on the return trip a flat tire leads to a trunk of porn and a bunch of lies. Annie's confident attitude quickly disappears when she realizes that Jasper, the nephew of the man she hit on prom night, is a student at West Beverly. Navid continues to run the Blaze News and assigns Silver and Gia to interview Jasper for a news piece about his uncle. Things get steamy when Adrianna confides in Teddy, resulting in Adrianna and Navid finally spending the night together. Liam finally finds a way to get revenge on Jen and reveal the truth to Naomi about their night together at prom.

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, but Silver feels differently. Navid's world is turned upside down when Adrianna reveals that she needs time alone, but turns to Teddy for attention. Jen continues to manipulate Naomi and manages to convince Naomi to lend her a large amount of cash. Jasper rescues Annie from a bad date and the two forge a bond that will be hard to break. Harry accompanies Ryan to a bar for some guy time and attempts to be his wing man.

Navid and Gia launch an investigation into student drug use at West Beverly for Blaze News, which leads them to Annie's boyfriend, Jasper leaving Annie torn over who to believe. Fresh off his break-up with Adrianna, Navid receives dating advice from Samantha Ronson while out with Liam, Teddy and Ivy at the Edison. Worried that Adrianna will relapse, Naomi and Silver enlist Navid's assistance. Dixon reveals his situation with Sasha to Debbie and Harry, prompting Debbie to do some investigating. Jen and Ryan meet up with Pharrell to watch a performance of N.E.R.D.

Annie leaves Debbie and Harry surprised when she informs them that she would like to invite Jasper over for dinner. Dixon decides to pass on the event as a result of his anger over Debbie's management of the Sasha situation. Meanwhile, Kelly shows support for Silver regarding the caring of Jackie despite the fact that she does not yet know if she can ultimately forgive her mother for all the pain she has caused in the past. Navid confronts Adrianna about her drug use, and a weekend camping trip leads to Ryan and Jen's relationship climbing to a new level. Also, Naomi is caught kissing Jamie by Richard and his mother, forcing her to come clean about her plans for CU admission.

Navid wakes up in the hospital but has no memory of who pushed him down the stairs. Adrianna visits Navid and following her conversation with him, makes a life-changing decision about her addiction to pills. Silver and Teddy bond over the loss of both of their mothers and unexpectedly get close. Liam, Dixon and Ivy learn that Naomi and Jen will be attending the horse races and devise a plan to finally reveal the truth to Naomi about her evil sister. Annie and Jasper sneak out even though Harry and Debbie have grounded her.

In an effort to put her inheritance to good use, Annie volunteers to organize a big charity fundraiser. When Naomi takes drastic measures to land her first event-planning client, her big plan back-fires. Meanwhile, Silver realizes she still has feelings for Navid, and Vanessa vows to make Liam a huge star after his agent drops him.

Naomi’s sister Jen arrives with her son for a surprise visit. Adrianna and Dixon land a meeting with a major movie producer to discuss music on his next film, but are sabotaged by Vanessa. Meanwhile, Silver gets accepted into New York University and Ivy attracts attention in the underground scene when she switches to a less conventional style of art..

Naomi is convinced that Annie’s new business partner P.J. is the perfect man for her, but discovers her sister Jen is also interested in him.. Adrianna and Dixon land a spot in a music festival, where Train performs and a record executive offers Dixon a recording contract. Adrianna tells Liam her suspicions that Vanessa staged the near drowning incident.

Dixon collapses while arguing in the recording studio with Adrianna. In the hospital, they run into Liam who is with Silver to support her during a test to detect if she has the breast cancer gene. Ivy finds out Raj still has cancer and is in the hospital, while Annie meets a new guy Caleb and discovers he is a priest.