Issues surface when Derek's estranged sister, Amelia, visits unexpectedly; Meredith and Derek continue to try to ease Cristina back into surgery.
The hospital is hit with an unprecedented crisis; Meredith and Cristina's surgical skills are put to the test.
Owen puts the residents through a rigorous trauma certification drill; Cristina is left alone to monitor an ill lung transplant patient.
After a burn victim unexpectedly dies in the ER, the Chief and board member Jennings question the residents, as all the staff members defend their actions in an effort to save their jobs.
Through Lexie, Meredith tries to get Derek interested in a patient's rare brain tumor; Callie ends up being annoyed when Mark and Arizona finally form a friendship.
