Dr. Cal Lightman is the world's leading deception expert. He is a scientist who studies facial expressions, body language, voice and words to discover whether someone is telling the truth or not. Lightman has developed the ability to spot "micro expressions" - small, nearly invisible facial expressions that reveal what a person is really feeling.

Lightman is the founder of The Lightman Group, a firm which often assists federal agencies, police, corporations and private individuals with their most difficult cases.

Dr. Gillian Foster is Lightman's partner in business and runs The Lightman Group with him. Foster has more of a focus on people's voice, words and psychology, while Lightman focuses on facial expressions and body language.

Ria Torres has developed her ability of deception detection by her own experience from her troubled childhood. Lightman is being a mentor to Torres, while also envying her, as she was born with the same skills that took Lightman years of training.