Lightman (Tim Roth, R) and Foster (Kelli Williams, L) go to Las Vegas to help locate a missing finalist in the World Series of Poker in the LIE TO ME episode "Fold Equity" airing Monday, Nov. 30 (9:00-10:00 PM ET/PT) on FOX. ©2009 Fox Broadcasting Co. CR: Isabella Vosmikova/FOX

The fall finale of Lie to Me airs tonight with a story surrounding an angry man who comes to Washington D.C. on a tractor, which causes pandemonium according to series star, Kelli Williams.

The actress says reading faces is just one of the challenges of the program, but very often the biggest hurdle to overcome as an actor is reacting to nothing but a blank monitor.  And Williams urges fans of the show to play along by checking out the faces of Tim Roth and her for clues as to what’s real and what’s not.

Williams actually met the person the show is based on, Dr. Paul Ekman, who can read folks like a book.  That didn’t sit well with the actress when she met the good doctor, who shared his own rules for dealing with loved ones.  He may put on the brakes with family, but she was an easy target for Ekman who understood her reservations at meeting him immediately.

Click onto the three media bars for Kelli Williams‘ comments on Lie to Me and the real person the show is based on.

Lie to Me airs Mondays, 9:00 p.m. ET/PT on Fox.