The residents and interns treat the victims of a massive explosion at an apartment building, while Alex investigated the cause of the accident. Mama Burke returned to collect her son's things just as Christina traded her wedding presents in exchange for surgeries. Lexie tried to have a heart-to-heart with an unwilling Meredith, and while Callie is overwhelmed with her duties as Chief Resident, Bailey searched for an outlet for her pent-up leadership skills.