Kate Mines

Costumed patients create a challenge for the doctors; Derek and Ben work on a new surgical technique; Richard asks a resident to perform his next surgery, angering Bailey.

Finn gives a health update on Doc, Meredith is assigned to work with Callie for the day while George gets paired with Derek, and Burke and Izzie continue to try to find a heart for Denny.

In the stunning conclusion of a two-part episode, Meredith furiously works to save the life of a paramedic trapped inside an ambulance, as her sister, Lexie, holds the life of a patient in her hands.

With Derek away, Meredith spends time with Amelia and finds out her true feelings about her time in Seattle. Bailey deals with the ramifications of her actions and Callie receives devastating news. Meanwhile, the residents panic after hearing that one of them will be fired.

Derek, Meredith, Arizona and Cristina receive news about the plane crash lawsuit; Richard avoids Catherine's advances; Jackson takes on one of Mark Sloane's former patients.

A new doctor at Seattle Grace puts others on edge; Arizona struggles with phantom limb pain; Meredith is faced with her worst fear.