Ben Reynolds, an FBI agent who's been pursuing a serial rapist terrorizing the Washington area, partners with The Lightman Group for its toughest case yet. Lightman infiltrates a prison to befriend Andrew Jenkins, a convicted criminal and a pathological liar who the serial rapist may be copy-catting. Meanwhile, Torres and Loker search Jenkins' fan mail, and Foster questions one of the rapist's recent victims.

Foster’s former patient, one of the founders of a social-networking app, comes to the Lightman Group when she thinks she’s being squeezed out by her partner. When she turns up dead a short time later, Lightman fights against the prevailing evidence to expose the truth behind the murder.

The son of a family of devout Jehovah's Witnesses is accused of killing his teacher after being caught fleeing the scene of her murder. Meanwhile, the team is hired by the Democratic National Committee to investigate a second case in which the Chairman of the House Ethics Committee is accused of paying for sex.

Lightman investigates one of his mentor's graduate students, whom he is convinced is a psychopath, while Loker and Torres look into a UFO sighting.

Lightman is an expert witness at the trial of a woman charged with murdering her high-powered, and much older, husband.

A missing woman leads the Lightman group to discover criminal activity in the adult film industry.

After a grisly shooting in a federal housing project, Lightman is hired to read the face of the paralyzed victim.

After a terrorist bombing outside of Washington, DC, FBI Agent Ben Reynolds calls on The Lightman Group to help identify those responsible and prevent more attacks. The case takes a personal turn for one member of the team and begs the question of whether honesty is indeed the best policy. Zoe helps Lightman with the investigation and both are concerned about their daughter's safety.

A protesting farmer parks his explosives-packed tractor near the US Treasury building. Meanwhile, Loker plays babysitter to third-graders stuck in the Lightman Group office, actress Felicia Day guest stars as their teacher. Miguel Ferrer guest stars as FBI ASAC Steele, Ben Reynolds' boss.

When Cal's old pal, Terry Marsh, comes to town, he brings plenty of trouble with him. Meanwhile, the rest of the team meets with some students from a prep school to determine if any of them are responsible for a threatening tape that was sent to the headmaster.

Lightman and his ex-wife, Zoe witness the execution of a murderer they prosecuted 17 years ago and face the possibility that they sent the wrong man to his death.

When Lightman is hired to find a corporate spy at a pharmaceutical company, he discovers a high-level conspiracy surrounding a new drug that could put thousands of lives at risk. The team is also hired by the State Department to assist with negotiations for the release of two Americans imprisoned in Yemen.

An Irish terrorist comes to Dr. Lightman to find out who killed his wife and daughter seven years ago, which reveals secrets about Lightman's relationship with Dr. Foster and his past job working counter-terrorism for the government.

When Assistant U.S. Attorney Zoe Landau, Lightman's ex-wife and Emily's mother, enlists Lightman to help investigate an arson case in which the only eyewitness is a 5-year-old boy, it quickly becomes clear that she and Lightman still have feelings for each other. Meanwhile, Foster and Torres question a rapper who is suspected of murder.

Lightman becomes involved in a dangerous game of cat-and-mouse when he meets a beautiful woman at an art gallery. Meanwhile, Torres is still reeling after her fatal mistake.

Lightman is hired by a terminally ill restaurant owner to find his daughter's killer as his dying wish.

Lightman goes head-to-head with the leader of a self-help empire to free a wealthy woman who may be under the control of the cult-like leader. When Lightman begins to investigate, things get personal as he suspects the group of threatening him and his daughter, Emily.

While defending a wrongly accused man, Lightman uncovers a dark secret that helps a damaged woman and her daughter.

Lightman tries to help a woman with early-onset Alzheimer's piece together her fragmented memories, but it uncovers a deadly secret.

The Lightman Group gets hired by Internal Affairs to investigate an incident that involves Det. Wallowski and her partner Det. Farr.

When Lightman investigates an explosion that killed six coal miners, he suspects foul play may be involved and goes below the surface to find the truth; the FBI seeks the Lightman Group's help with another case.

Lightman tries to stop a man intent on revenge from robbing a bank.

Lightman, Foster and Reynolds travel to Las Vegas to help locate a missing finalist in the World Series of Poker. Lightman uses his skills to read the other competitors' faces to figure out which one knows about the disappearance. Meanwhile, Loker and Torres analyze Loker's new relationship, and as a result, get closer to each other.

Lightman investigates three high school students responsible for a deadly traffic accident.

In the wake of a building collapse in a small town outside Washington, Lightman is brought in to determine who is at fault, and he discovers a massive cover-up. Meanwhile, the team is hired by a "dot-com" billionaire to determine if his girlfriend loves him for the right reasons.

A fighter in an underground club is found dead; Foster discovers a troubling secret.

A wealthy woman asks Lightman to look into her new boyfriend's background.

After a federal witness is killed, the US attorney arrives at the Lightman Group to take the next witness in line, Reynolds, into protected custody. Cal feels that the US Marshals Service cannot protect Reynolds, so he takes him "hostage" and demands that he be able to run the investigation into the witness's death. During his investigation, he finds out that while undercover Reynolds did drugs and killed a man and wants to keep it a secret to avoid prosecution after he finds out that his handler (Alicia Coppola) did not properly report the event. Through his own undercover operation, Cal records the handler admitting that she led Reynolds to believe that everything was all set legally, and the US attorney subsequently takes her into custody. Meanwhile Loker and Torres discover that the original witness was killed after the cell phone that his mistress provided was tracked to his safe house's location.