Marc Blucas will guest star on an episode of Lie to Me this fall.

The actor - who has appeared on House and is best known as Buffy's boyfriend on Buffy the Vampire Slayer - has been cast on the fifth installment of the show's second season.

He'll portray Jack Rader, a deception expert who was once Lightman's protege... until an unexplained issue caused a rift in their relationship.

"With Lightman on vacation, Rader is called in to assist on a case... he might just have an eye on [Lightman's colleague] Foster, and he might just try to poach some of Lightman's staff," said a network represenative.

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