'Perception': Cary Elwes Guests As An Imaginary World War I Code Breaker (VIDEO)

"Perception" (Mon., 10 p.m. ET on TNT) may have hit on a way to stand out from the crowd of crime procedurals across the television airwaves. One of the main conceits of the Eric McCormack drama is that his character -- a paranoid schizophrenic -- is aided in his crime-solving by his hallucinations.

This week, that vision came in the form of guest star Cary Elwes as a World War I codebreaker. He was on hand, fully self-aware that he was little more than a figment of Dr. Pierce's (McCormack) mental illness, throughout the episode to aid Pierce in piecing together the clues.

The conceit of these weekly hallucinations open up a lot of fun casting possibilities for the show. Producers and casting directors can throw their net far and wide to reel in almost any type of celebrity or personality to appear either as themselves or as a distinct and unexpected character like a World War I codebreaker.

Watch "Perception" every Monday at 10 p.m. ET on TNT.

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