A high school student is seen running from the home of a murdered teacher. Elsewhere, the chairman of the House Ethics Committee is believed to have been hiring a prostitute.
Cal works on the claim that a sergeant raped a female soldier, while basketball fan Gillian investigates a case in which a college alum used bribery to get him to sign on with the school.
The Lightman Group head to a competitive prep school when a federal judge's daughter is murdered. Meanwhile, a pilot from NASA has been accused of crashing his plane intentionally.
The team is asked to keep watch over an ambassador from South Korea while here for his son's wedding, and is also running for president in his native land and has received assassination threats. During the ceremony a shot is fired and the ambassador's son is hit, which leaves Cal to believe it wasn't just a case of bad aim. Besides, everyone at the wedding celebration seems to have a secret they are hiding.
Ria and Cal question a former gangster. Meanwhile, Eli and Gillian investigate when a firefighter is killed on the job.
The Lightman Group is called when a family is scared of their 11-year-old daughter when she goes missing. Loker and Torres are called to see if a peace-activist isn't actually a liar. Loker must put his feelings aside for once and make a decision whether or not that his mentor isn't really a fraud.
Lightman's oldest friend, asks him to find the researcher that leaked a formula to fight diabetes. Foster and Loker helps the DOD in negotiations with the Sudanese authorities to get two Americans back who have been arrested for possession and are on the brink of being sentenced to death. Eli and Gillian realize that the DOD wants the woman more than her brother. There is only one explanation: she's a spy.
While waiting in a traffic jam, Cal realizes that the traffic is stopped due to an accident. He goes to investigate and learns that it was a suicide. However when he sees an old acquaintance that should not be here, he surmises that there is more to it. She tells him that there's been another suicide in the exact same sport and that thr first one was related to the second one. Cal proposes his help.
Eli and Gillian are hired by the SEC to find out if Hollin who has agreed to plead guilty to numerous charges has told them everything.
FEMA Commander Stevens calls the Lightman Group in to help finding three missing construction workers after a building being built collapsed. All the major players, FEMA, Civil Engineer and the mayor blames each other for the catastrophe. Cal finds out very soon that the worker who told them where the three missing should be was lying, they have to stop and let the dogs in. Eli and Ria interview a potential client. Jason McLean, the founder of a very successful networking website, asks them to find out if the woman he is going to marry has lied about what she knew before meeting him. While they usually refuse these kind of cases, the check McLean gives them tips the balance in his favor.
Cal is hired by his ex-wife, an assistant district attorney, to investigate an arson case which a childhood friend, now a famous TV reporter, has been accused as the suspect. His word is based on that of his 5-year old son. Meanwhile, Foster and Torres investigate a drive-by-shooting involving rival rappers.
Cal is hired to investigate when an undercover cop chasing a drug suspect accidentally shoots a teen instead. Meanwhile, Loker's lie during the recent Ponzi-scheme investigation could come back to bite him when Cal informs him they may become deposed in a lawsuit because of the matter. Also, Cal's suspicion that Foster's husband is having an affair is renewed when he spots him with the same woman he had seen him with before.
FBI agent Ben Reynolds, is in pursuit of a serial rapist who is terrorizing the Washington area. He partners up with the Lightman Group for one of his toughest case to date. Lightman infiltrates a prison to meet Andrew Jenkins, a convicted criminal an pathological liar in which the serial rapist may be imitating. Meanwhile, Torres and Loker search the fan mail of Jenkins, while Foster interviews a recent victim of the rapist.
FBI agent Reynolds enlists the Lightman Group to help find the perpetrators of a terrorist attack outside of Washington, DC. For one team member the case becomes very personal. In addition, Cal and Zoe are afraid that their daughter may be in danger.
The Lightman Group looks into a murder case in which a woman with a multiple personalities disorder is involved and the group must decide whether she is a witness or the killer. Meanwhile, the U.S. government hires The Lightman Group to interrogate a potential Supreme Court nominee.
Zoe has the Lightman Group look into a college athlete accused of rape. Meanwhile, Foster and Loker head to a religious compound in order to determine whether or not it is actually a cult.
Lie to Me is in Mexico this week and while there, Lightman and Emily work on a case involving a missing American woman Marla who has been missing for 2 days. She has a daughter that is in Mexico too. Lightman invites Torres in on the "fun" as well. Meanwhile, back in the United States, Foster looks into tainted blood in D.C. hospitals and needs to go through different people who could have tainted the blood. Getting down to the final details in both cases proves a little bit of cat and mouse but in the end everything works out for the best. Lightman plays a little bit protective of Emily throughout their trip and in the end both take a little to enjoy their well deserved vacation.
The Lightman Group work on a case involving a Eric Matheson, a man accused of killing is wife, and they have to find him before he hurts another person. But Eric finds them when he takes Lightman hostage and holds him there while he tries to clear his name. There is a spiderweb of drug dealers, to loan sharks that Foster and the rest of the team have to go through to find all the clues to who the real killer was and who should be the one going to jail. The team become creative and find enough evidence to clear Eric of the crime.
A old friend of Lightman's with a dicey record pulls him into a dangerous orbit, that of a criminal who wants to misuse Lightman's capabilities, putting stress on their friendship, his loyalty to his friend, as well as his relationship with Agent Reynolds. The Lightman Group also investigates homicidal threats that appear to be coming from a high school student.
Two years ago, Agent Reynolds was deep undercover, acting as an enforcer for an extortionist. When a witness in the case is murdered despite being in protective custody, Lightman and Foster demand to be brought in on the case, first to assist in finding out who leaked the details of the custody, then to protect Reynolds, who refuses to testify, from actions he took which he believed were sanctioned, yet there is no record of his authorization papers in the Federal documents on the case. What did Reynolds do that was so horrible?
It is Black Friday and the team investigates a lawsuit that for 2 murdered customers. Meanwhile, Max Roland, A troubled teen that believes he was abducted as a baby comes to the office of Lightman Group to help him uncover the secrets of his past. Loker investigates the origin of a deadly stampede that occurred at an electronics mega-store the day after Thanksgiving. The company is offering to give the Lightman Group a percentage of the money they save in their findings. The cases go cold and hot and the team must work really hard to uncover the truth and make the right decisions.
Christmas Time and everyone is in the Christmas spirit with a Secret Santa drawing. That is until Lightman gets news that he is going to have to go to Afghanistan where 2 Marines are kidnapped and to interograte a captured prisoner who claims to be Franco Vincent an American. Lightman doesn't tell Emily and leaves for Afghanistan. A lot of secrets are revealed about Franco's past and motivations. The team is watching via satellite to assist Lightman. After all of it, Lightman uncovers the truth and tries to make the best of a bad situation.
Lightman, Foster and Reynolds are going to Vegas and this time, a finalist from the World Series of Poker in Las Vegas to take part in the Championship disappears. A man is killed and Jake Hartland doesn't know where to go. In the midst of professional liars, Lightman has his hands full with trying to pick the truth from the lie. In the Meantime, a hint of romance flickers between Loker and Torres. The lying continues and Lightman has to keep hidden his gamble with Reynolds and the Roulette table. But that is quickly found out as well. The players are eliminated one by one by Lightman's uncanny talent of spotting deception and the game gets interesting.
A disgruntled farmer parks his tractor, that's packed with explosives, near the Treasury Department building, causing Lightman and his team to make some crucial life-or-death decisions. Meanwhile, a field trip for the third-grade gets stuck in the Lightman Group offices, and Loker is forced into playing babysitter, all during a political protest in Washington DC.
Lightman tries to prove that a brilliant and charming in front of psychology graduate students and meets a match that he can't read. But pick him out as a psychopath. Two Sophomore girls are missing and student Martin Walker is the suspect. Meanwhile, Torres and Loker investigate a UFO sighting and sift through the video of the incident from one of the students. They have to draw the government out to save Mr. Hickson's job. Lightman hunts down Martin to uncover the truth but in the mix, runs into a little bit more trouble then he anticipated when he is caught in a tough spot that could have dyer consequences.
After Lightman's former Pentagon colleague is killed in a car bomb, Lightman and Foster are forced to revisit a series of events from their past, including the therapy sessions that brought them together.
Lightman is called upon to determine the truth in a case that involves a multi-billionaire and a woman who can't remember the last 40 minutes of her time with her husband who is now dead. Lightman battles against Zoe and finds that there is something that Claire, the recent widow, is not telling. Lightman tries to get the whole truth out of her before the end of the trial.
When an ex-soldier from Iraq almost kills his son, Lightman Group is called in to examine him. He has PTSD (Post-Traumatic Stress Disorder) and Lightman uses new tactics to get the truth out of him. He thinks that someone is out to kill him and Lightman must find out the truth before he hurts himself or others.
When Officer Nick Hardy is shot and is paralyzed, Lightman is called in to assist the FBI to read what Nick is telling them. Nick recognizes the boy who shot him but as Lightman and Reynolds get further in the investigation, some men in blue are involved. Meanwhile, Clara has taken an interest in what Lightman does and wants him to teach her how he does what he does. Does she have other motives to this request or not?
Torres is forced to revisit her troubled past when her half-sister is incarcerated in a juvenile corrections facility.
After a young woman dies at a gubernatorial campaign rally in Virginia, The Lightman Group is hired to assess whether the case is a failed assassination attempt or a well-disguised murder plot.
Lightman risks being exposed as a gambler in an underground fight club when one of the fighters is found dead. Meanwhile, Foster's romance with Burns (guest star Max Martini) hits a snag when she uncovers a troubling secret.
Lightman and his ex-wife, Zoe (guest star Beals), witness the execution of a murderer they prosecuted 17 years ago and face the possibility that they sent the wrong man to his death
Foster's boyfriend (Dr. Dave Burns) gets into trouble and the only way Cal can save his life is to tell the truth.
The Lightman Group is trying to track down a missing girl. The girl is known to have been an actress in the adult entertainment industry. Lightman and Foster visit the production company to find out more.
When a journalist friend of Cal Lightman is murdered, the investigation tests his relationship with the FBI; Emily's interest in dating makes Cal uncomfortable.
Lightman infiltrates a group of bank robbers to prevent the actual robbery from succesfully taking place.
Lightman defends a wrongly accused man from an increasingly hostile mob. In the process of exonerating him, Lightman uncovers a dark secret that helps a damaged mother and her daughter begin the healing process.
The Lightman Group is hired to examine police profiling techniques in the wake of an incident involving Wallowski, and Internal Affairs attempts to leverage Lightman's relationship with Wallowski to get him to incriminate her.
An art museum hires the Lightman group to determine wheter their personnel is trustworthy because of an upcoming major exhibition.
Torres feels bad when a robbery attempt is made on the museum, which she didn't anticipate. Lightman meets a beautiful woman who turns out to be playing him to distract him and get what she wants.
When a mining incident occurs, The Lightman Group is hired to find out if it really was an accident or if it was intentional. Lightman goes underground to see if the miners are hiding anything about the incident.
Meanwhile, Foster is clearing Lightman's name with the FBI, who discovered that Lightman has been participating in underground poker games.
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.
A woman with early Alzheimers' is hit by Lightmans' car while Emily is driving and texting at the same time. The woman seems to be confused. Emily calls Cal to assist her. The woman seems to believe that people close to her have all been killed by a man called Charlie. Lightman further investigates what's going on.
After a young girl gets shot during the robbery of the diner, Lightman and Foster think that it was no accident, but premeditated. Since it was a family restaurant, they investigate the family. The current owner is dying of cancer and his will regarding the restaurant ownership strikes Lightman as a motive for the murder.
Lightman is called to a mental hospital to determine if a patient is being held against his will. Attempting to have the patient released, Lightman finds himself descending down a path that forces him to question his own sanity and brings him face-to-face with his own past.
Lightman is hired by a wealthy woman to do a background check on her new boyfriend, so he digs deep into the man's past to find out the truth about this social chameleon.
Lightman is hired to investigate three high school students responsible for a fatal traffic accident, which takes a turn for the better when he finds the heroic paramedic who was first on the scene.
When a baby abduction is mentioned on the news, Lightman and Foster study the faces of the parents. Lightman thinks that there is foul play from one of them. They dig further into the case to help out with the police investigation of the abduction.
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.