Amrapali Ambegaokar

Derek and Meredith get ready for their wedding; college students injured in a car accident are admitted to the ER; Izzie starts experiencing familiar symptoms.

The residents and interns treat the victims of a massive explosion at an apartment building; Mama Burke returns to collect her son's things; Lexie tries to have a heart-to-heart with unwilling Meredith.

George and Izzie test their romantic chemistry; Derek asks for more than a physical connection with Meredith; Mark develops a crush on a fellow surgeon; Callie finds her role as chief resident jeopardized.

A plumbing leak becomes a flood, causing chaos at Seattle Grace; the chief tries to implement new teaching policies; George tries to take his residency exam again; Derek hopes to move Meredith's roommates out of her house.

Derek finds an old diary of Meredith's mother; Callie anxiously prepares for her first real date with Erica; Cristina stumbles into a part of the hospital that she and the other residents have never seen.

Izzie returns to work; Seattle Grace residents position themselves to avoid layoffs; Cristina tries to work with Arizona in the pediatric ward.