When Dixon tries to slow down the pace of their relationship, Silver takes a trip to Kansas to learn what he was like before coming to Beverly Hills. Unfortunately, her fragile mental state gets her involved in a difficult situation. Meanwhile, Kelly once again faces her troubled mother Jackie.

Kelly and Silver are shocked when Donna arrives in town. Annie and Dixon take a road trip to visit someone from Dixon's past while Ethan spends his spring break working for Habitat for Humanity. Naomi also decides to work for Habitat when she learns that Liam will be there.

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.

With the help of Teddy, Jackie surprises Silver with a half-birthday celebration that takes her back to her childhood birthday parties. Navid witnesses Adrianna buying drugs from Jasper, forcing Navid to confront him about being a drug dealer. Dixon is determined to confront Sasha about her miscarriage, forcing Debbie and Harry to reveal that Sasha lied about being pregnant. Annie and Jasper profess their love for each other and decide to take their relationship to the next level. After getting into a fight on the beach, Liam, with the help of Dixon, Teddy and Ivy, devises a plan seek revenge on Jen.

Annie and Liam test out the waters with his new boat, where they share their darkest secrets. Little do they know that someone is nearby and decides to share an explosive flame of gasoline with Liam's boat. Liam finally tells Naomi their relationship isn't working, leaving her more alone than ever. After a late-night dance, Naomi turns to someone for help, but he ultimately helps himself to her. Adrianna is offered the opportunity of a lifetime but is torn about the direction to take after Navid confesses his true feelings for her. Teddy discovers that Spence tried to bribe Silver and takes it upon himself to seek revenge in a most confrontational way. Ryan is delivered some mind-blowing news about his past with Jen when a mysterious package arrives on his doorstep, causing him to head down a disasterous path. Dixon and Ivy's summer vacation plans in Australia comes to a screeching halt when he confesses to kissing Silver. Harry and Debbie face a major hurdle in their marriage when she learns the truth that he has been hiding in order to protect Dixon.

Naomi, sick of hiding her relationship with Max and afraid he might be cheating on her, follows him to an academic decathlon event, to confront him. Silver begins to behave erratically, which worries Navid and secretly pleases Adrianna. Raj helps Ivy overcome her fear of the water, while Annie starts working for lonely, aging actress Marla, and forms an unlikely friendship with her.

In the season four premiere, gang from Beverly Hills have graduated from high school. Naomi has spent the summer dealing with the shocking news of her pregnancy and quickly discovers she doesn’t have the status at college that she did in high school. Annie receives some unexpected news that keeps her in town, while Liam returns from his summer away ready to commit to Annie. Dixon finds himself without a roommate or a place to live, while an unexpected visitor tests Navid and Silver’s relationship after they move in together. Adrianna comes back to town looking for redemption, which she soon learns will be hard to earn back. Ivy and Raj struggle to deal with Raj’s health getting worse, while Teddy struggles with coming out to his family.