Meredith and Lexie's father returns to Seattle Grace with stomach pains and a new girlfriend; Alex butts heads with the new OB; Mark bribes Jackson for information on Lexie.
The team investigates when children come across the body of a missing Marine in a frozen lake, and soon discover three more fatally shot bodies.
Lightman heads to war-torn Afghanistan to determine whether an American detainee is telling the truth about the location of two captured Marines.
Ned falls in love with a young dancer whose family is hiding a secret. Melinda needs to uncover what that secret is before it's too late.
Jack and the team search for a boy that disappeared on a subway train en route to Yankee Stadium for a birthday celebration.