Annie, humiliated by the mass sext message, sets out to prove that Naomi sent the message. Harry and Debbie try to talk about Annie’s situation, but their discussion only causes more tension, leading Harry to confide in Kelly about his family issues. Dixon meets the girl of his dreams, Sasha, but hides his true age in order to get to know her. Meanwhile, Silver continues to try to get over Dixon; Adrianna and Navid deal with Teddy; and Liam begins working on a mysterious project.

Blair ends up with Georgina as as her roommate in the dorms at NYU. While Serena and Chuck come to blows, so she joins forces with Chuck’s enemy, Carter. Nate and Bree try to take their relationship up a gear despite the animosity between their families.

A growing scandal forces Clay to defend Nathan, while Haley and Mia has problems with protecting Red Bedroom Records from going down. Brooke is looking for a new face of her clothing line, and she decides to move in together with Julian, and Dan unveils his new bride.

Elsewhere, Angela worries Nathan will discover his real identity; Matt has a surprise visitor; Tracy and Noah team up to investigate a crime; and a friend asks Peter for help.

Sheldon flees back to Texas in disgrace when he learns the guys tampered with his arctic expedition data, forcing the guys to follow him and threatening Leonard’s hopes for a romantic encounter with Penny.

When Marshall and the gang finds out that Barney and Robin are hesitant to define their relationship, Lily forces them to confront their biggest fear. Meanwhile, Ted is anxious about teaching his first lecture at Columbia.

House checks in the psychiatric hospital and meets a few new characters including his roommate Alvie (guest star Lin-Manuel Miranda) and Dr. Nolan (guest star Andre Braugher).

Claire garners attention at college following an odd death in the fourth-season premiere.

Drama eyes a part on Melrose 2009 and asks Lloyd if he can get him out of his current gig on Five Towns. Still irate over Lloyd’s job offer, Ari goes to war against Lloyd to get Drama out of his contract. Citing their trust issues, Ashley asks Eric if she can read his e-mails so that they can have an open and honest relationship. Turtle feels guilty about his love triangle, of sorts, with Jamie-Lynn and a UCLA co-ed.

Mystic Falls begins the preparations to celebrate the passing of a comet. Vicki recuperates in the hospital from her injuries. Stefan uses his abilities to erase Vicki’s attacker from her memory, but is interrupted by Matt. Mr. Tanner warns Aunt Jenna about Jeremy. Elena and Damon meet for the first time at the Salvatore house and his revelation on Stefan’s past brings Elena closer to the truth. Damon finds his next victim in Caroline.