The interns each react differently to a mass-casualty incident. Meanwhile, George crosses the professional line with Callie, Cristina asks Burke to keep quiet about their engagement, and Richard dons a new hairstyle.
Meredith is still reeling from the time spent with her mother, and Derek is getting concerned. Meanwhile, Cristina seems to be delaying her announcement, and everything is put aside when a disaster occurs and each intern is faced with treatment decisions and tasks they are not equipped for.—layle