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.

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.

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.

A young woman approaches Lightman at his book signing, believing she has seen a murder. Lightman finds that the woman has multiple personalities, and he believes that one of her personalities witnessed the murder. Lightman passes off helping Agent Reynolds vet a potential Supreme Court nominee, instead choosing to pursue the case of the multiple-personality woman. The case is passed on to Torres, whom the nominee does not treat with respect due to her age. Torres puts her preconceived judgments about the man aside when she analyzes the facts. Lightman unlocks the woman's original personality, who helps Lightman find the original murderer. Zoe informs Lightman that she is taking their daughter, Emily, and moving to Chicago to open a law firm. Lightman buys out her stake in The Lightman Group so that she can start her own practice in town.

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.

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

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

Zoe enlists Lightman to help with her client -- a 22 year-old black star college football player who has been accused of statutory rape with a white 16 year-old girl. The case hits home for Lightman, who learns that his daughter Emily was friends with the group of girls who attend these college fraternity parties. Through the course of their investigation, Lightman and Torres determine that Zoe's client was set-up by the girl, whose friends leaked the video of the hookup. Lightman figures that the man did not know the girl was underage, noting that his face showed that he knew he shouldn't find underage girls attractive. Meanwhile, Foster and Loker travel to a religious compound to determine whether its claim of IRS exemption is valid. They believe the head of the compound is holding the women against their will. Foster facilitates the escape of one woman and her children, and faces the wrath of both Loker and the government. At the end, the girl's father believes the system is protecting the football player, and decides that someone has to pay. He shoots the prosecutor that dropped the charges against the football player, with whose death the episode ends.

Eric Matheson (Garret Dillahunt) is determined to prove that he didn't murder his wife. Torres is assigned to investigate the murder, and goes to the house of the victim's sister. Matheson finds Torre's car and gets into it after she forgot to lock the door. When Torres returns, Matheson holds her at gunpoint, instructing her to drive to the Lightman Group offices. Cal makes a deal with Mattheson, asking him to let all the employees go as long as he helps prove Mattheson's innocence. Mattheson complies, and Foster, Loker, Reynolds and Torres attempt to solve the case, while Loker has second thoughts about not calling the authorities. Cal and the team find out that Mattheson was actually innocent, and that his wife was actually killed by a creditor. Mattheson demands that he sees the creditor, saying he will either take his life or Cal's. Cal pleads for Mattheson to kill him, but Foster, Loker and Reynolds trick Mattheson into letting his guard down after a disguised Loker pretends to recount the last moments of Mattheson's wife's life. As Mattheson is in a moment of rage before killing Loker, Reynolds draws his gun and shoots Mattheson, disarming him. The episode ends with Lightman at Foster's home, asking if he could sleep in her spare room for the night.

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.

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.

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.

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

Cal Lightman questions his own sanity while he tries to get a patient released from a mental hospital.

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.

Lightman and Torres interrogate an imprisoned gang leader who claims to be rehabilitated. If the gang leader is freed, he might help fight inner-city violence or return to his life of crime. Foster and Loker investigate the death of a firefighter who was killed in the line of duty.

Lightman becomes obsessed with his investigation of two young women who committed suicide. Meanwhile, the team tries to recover billions of dollars for investors who were bilked by a Ponzi scheme.

While on vacation in Mexico with Emily, Lightman becomes involved in the case of a missing American woman, who is a single mother on vacation with her daughter. Upon investigation, Lightman learns that the mother got herself involved with an illegal fertility broker and he manages to find her just in time. Back home, Foster investigates D.C.-area hospitals with Lightman's rival, Jack Rader. They try to uncover the reason that five people have grown gravely ill after receiving blood transfusions.

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.

Lightman and Foster investigate the disappearance of an 11-year-old girl who may have been murdered. Meanwhile, Loker and Torres must determine whether a famous peace activist is who she claims to be and if her bestselling memoir is true, but Loker's attraction to the socially conscious woman may be clouding his assessment of her.

The Lightman Group gets embroiled in the controversial case of a policeman who shot a potentially innocent teenager. Meanwhile, investors who were bilked by a Ponzi scheme are suing The Lightman Group for botching the recovery of their money,

Cal spends the holidays in Afghanistan, where he relies solely on an American expatriate to help a mission to find a pair of missing Marines.

When a female soldier charges a commanding officer with sexual assault, Lightman is brought to Fort Meade to find out if there's any truth to the accusation. Meanwhile, the Lightman Group is hired to determine whether the young star of a college basketball team accepted a bribe to play for the university.

The murder of a teenage girl – who is the daughter of a powerful federal judge – leads The Lightman Group to a highly competitive college-prep school where getting to the head of the class means everything. The team also investigates a NASA test pilot accused of intentionally crashing a $250 million aircraft

At a state wedding, Lightman and his team work to prevent the assassination of a South Korean ambassador. But when someone else is shot, Lightman exposes long-held family secrets and lies to identify the assassin.