John Prosky

After a doctor is found dead at a golf course, the CBI team searches for a killer amongst a hospital's staff and patients. Meanwhile, when LaRoche is placed in charge of the CBI, his first act of business is to name Cho the new team leader.

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, and Victoria sets a trap for Emily.

The SSR discovers the gas cylinder in the cinema and realizes that Ivchenko may be planning an attack. Howard Stark returns and explains that he had developed the gas to give American soldiers extra stamina during war, but it caused psychosis.

Sookie fears the worst for Bill, whose fate now lies in Lorena's hands. Jason's romance with Crystal hits a snag, as does Lafayette's with Jesus.

When a body is discovered in Atlanta covered in scratches, the BAU finds that this death and subsequent murders could be linked to an UnSub with an obsessive skin disorder.