"Faceless, Nameless" -- While profiling a killer with a personal vendetta against an emergency room doctor, Agent Prentiss (Paget Brewster) is the first to realize that Hotch is missing, on the fifth season premiere CRIMINAL MINDS.
CM Fanatic has an interesting discussion about what will happen in season 5 now that they have one actor on crutches, one actor banged up and a new actor joining the mix for a six episode gig. Du can read other people's guesses and add your own :)