Cristina returns from her "honeymoon" (with Meredith) and begins looking for Burke. At the hospital, new chief resident Callie welcomes a new batch of interns---including George, who is repeating his intern year, and Meredith's half sister Lexie (Chyler Leigh). Meanwhile, Richard resumes his post as chief of surgery, while Bailey tries to acclimate herself to her new duties at the hospital; Derek, at an impasse with Meredith, looks to fellow doctors for friendship. ~ Paul Droesch, Rovi