2x16 It's the End of the World
The episode begins with a dream of Izzie, Cristina, and George in the shower together. It's George's dream. Meredith refuses to go to work. She has this feeling that she will die. George and Izzie can't get her out of bed, they have to call in Cristina. Once at the hospital, the premonition seems to have some validity. A trauma victim is brought in by a paramedic with her hand still stuck inside him to stop the bleeding. As Alex soon discovers though, her hand isn't the only thing inside of him -- after trying to make a homemade bazooka, he's also got a piece of unexploded munitions inside of him. This places the hospital on Code Black, which essentially shuts down the surgical wing -- save for the one operation that has already begun: Derek and Cristina operating on the brain of a man who happens to be Bailey's husband.