When you scratch your chin, wring your hands, wrinkle your nose or swallow too much, Dr. Cal Lightman (Roth) knows you're lying. He doesn't just think so, he knows so. As the foremost deception expert in the country, Dr. Lightman can uncover the deepest secrets and crack the hardest cases. More accurate than any polygraph, he knows whether those in front of him, be they family, friends, criminals or complete strangers, are honest or not. Dr. Lightman heads up The Lightman Group, a private agency contracted by the FBI, local police, law firms, corporations and private individuals when they hit roadblocks in their searches for the truth. Joining him at the agency are a variety of experts in the field of behavioral evaluation: Dr. Gillian Foster (Williams) is a gifted psychologist and Lightman's professional partner, a woman whose guidance he needs whether he knows it or not; Will Loker (Brendan Hines) is Lightman's lead researcher who practices, radical honesty, at all times; and Ria Torres (Monica Raymund) is the newest member of the team, selected for her innate ability to read body language and catch certain clues that her colleagues may miss.