The first season of "90210" will conclude on May 19 with a misunderstanding. Liam, being the bad boy that he is, said that he is not the boyfriend of Naomi, and thus Annie takes the fall. Naomi and Liam have revealed their honest feelings for each other and she decides to host an after-prom party at her new house, much to Jen's disapproval.
Showing up late, Naomi searches for Liam but is speechless when she finds him finishing up some business in her bedroom. A furious Naomi confronts and accuses Annie of sleeping with Liam, causing Annie to finally snap at Naomi and all the party-goers before leaving the party in a rage and doing something that will haunt her for the rest of her life.
Meanwhile, Adrianna and Navid spend their prom night in the delivery room and Brenda shows up to offer support. Dixon and Ethan get into a fight when Dixon accuses Ethan of having feelings for Silver. Harry and Debbie chaperone the after-prom party but leave early to lend their support to Adrianna at the hospital, along with Kelly.