Following a terrorist attack outside Washington, D.C., FBI agent Reynolds enlists the Lightman Group to find the perpetrators. Then the case becomes personal for a member of the team. In addition, Cal and Zoe fear that their daughter could be in danger.

An FBI agent enlists the Lightman Group in the hunt for a serial rapist. Cal's assignment: infiltrate a prison and befriend a convict whom the suspect appears to be copycatting.

An undercover cop chasing a drug suspect mistakenly shoots an innocent teen, and Cal is hired to determine the man's intentions. Meanwhile, Loker's lie during a recent Ponzi-scheme investigation could come back to haunt him (and Torres as well) when Cal tells them that they'll be deposed in a lawsuit over the matter; and Cal's suspicions that Foster's husband is having an affair are raised anew when he sees him again with the woman he had seen her with before.

Cal's ex-wife, an assistant U.S. attorney, hires him to get to the bottom of an arson case in which the victim accuses a childhood friend, who's now a famous TV reporter, of burning down his house. He bases the charge on the word of his 5-year-old son. Meanwhile, Foster and Torres investigate a drive-by shooting tied to a feud between rival rappers.

When a building under construction collapses, Cal and Gillian must determine if someone on the scene might have sabotaged it and how. The safety of workers still trapped inside could depend on it. Meanwhile, an Internet entrepreneur planning to propose to his girlfriend wants to know if she really loves him or if she's after his money.

Cal becomes obsessed with the suicides of three young Indian-immigrant women, and Loker takes an unusual interest in the Ponzi scheme he and Foster are investigating. The scheme's operator, who's dying of cancer, insists that he is solely responsible for it, and that all the money is gone. But Foster---and especially Loker---aren't buying either assertion.

Lightman is hired by an old friend to find a corporate spy at a pharmaceutical company, then gets mixed up in a conspiracy surrounding a new drug that could put thousands of lives at risk. Meanwhile, the State Department hires the team to assist with negotiations for the release of two U.S. citizens imprisoned in Yemen.

While Lightman and Foster probe the disappearance of an 11-year-old adopted girl, Loker and Torres must determine whether a Ugandan peace activist is who she claims to be. One problem: Loker is a fan of the woman, and they become attracted to each other when they meet.

A governor weighing a pardon for a reformed gang leader imprisoned for killing a cop hires Cal to determine if the guy has really reformed. Meanwhile, the death of a black probationary firefighter in a burning building might not have been accidental. Gillian must find out if it was murder and, if it was, who did it.

The team is assigned to protect the South Korean ambassador, a presidential candidate in his country and the object of death threats, during his son's wedding. The ambassador isn't shot but his son is, and Cal doesn't think it was the result of bad aim. Besides, everyone in the wedding party seems to have something to hide.

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.

While Cal tries to determine the truthfulness of a female soldier's rape accusation against her sergeant, basketball fan Gillian probes a charge that an influential college alum bribed a promising inner-city prospect to attend his school.

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.