Psych: Season 6, Episode 6

6 - 6: Shawn, Interrupted

It's another undercover assignment for Shawn and Gus when SBPD asks them to infiltrate the local mental hospital. They must prove that the billionaire recently found "not guilty by reason of insanity" after he murdered his assistant is just as sane as they are. Well, as sane as Gus at least.