Dr. Cal Lightman, an expert in how facial expressions and body language betray emotions, solves cases for law-enforcement agencies and whoever else hires him in this whodunit. In the pilot, a high-school teacher is murdered, and one of her students is caught running from her house; and the chairman of the House Ethics Committee is accused of patronizing a prostitute.

The murder of a federal judge's teen daughter leads the Lightman Group to her highly competitive prep school. Meanwhile, a NASA test pilot is accused of intentionally crashing a plane.