John Prosky

Izzie seems to be getting over Alex when she shares an undeniable chemistry with Denny Duquette, a patient who's awaiting a heart transplant, and George treats Bex, a young teen hermaphrodite.

Emily learns the identity of a key conspirator against her father; Victoria sets a trap for Emily.

Jack begins closing in on the location where Teri and Kimberly are being held hostage. Meanwhile, Teri and Kimberly create a shock of their own as things get violent at the compound. Also, Senator Palmer's worst fears are realized when he uncovers just how far his campaign backers are willing to go to protect him.

Holly pushes Saul and Sarah to their limits; Kevin encounters prejudice in the workplace for the first time; Justin struggles with a hero's welcome from a soldier he saved in Iraq.

A body is found covered in scratches, leading the BAU to believe that the person responsible has a chronic skin disorder.

Peggy is faced with Leviathan's fury as she tries to save Howard Stark -- and the world.