Cal agrees to testify for the prosecution until he learns that his ex-wife is representing the innocent defendant: a beautiful younger woman accused of killing her much older, and extremely wealthy, husband.

A decorated war hero who is suffering from Post-Traumatic Stress Disorder claims that someone is trying to kill him, and Dr. Lightman is brought in to investigate.

Pathologist Pierce links a string of seemingly accidental deaths through cryptic music tattoos. As he brings Harry and Fergus in on the case, secrets unravel, and an act of revenge spirals toward another kill.

Two burglars witness politician Nicholas Samson kill a woman and seek Harry's help. As suspicion grows and evidence surfaces, Harry faces a powerful enemy.

The kids struggle with their new lives as Runaways, but find a hideout. Alex goes to work for Darius while PRIDE plots to kill Jonah. Jonah initiates a plan to build a new box.

Karolina, Nico, and Molly try to retrieve the Staff of One, but Tina puts up a fight. Karolina grows closer to Jonah while Alex and Livvie share a kiss.

Alex, comfortable in Compton, is betrayed. Jonah gives Leslie a mission to retrieve his DNA from the Yorkeses while Catherine exacts vengeance. Molly sneaks out to fight crime.

Antonio crosses a line that puts the entire team at risk.

Voight and Ruzek lock horns over how to handle the aftermath of the Antonio situation. Meanwhile, a series of violent carjackings turns deadly, and Ruzek must rely on a C.I. he grew up with to help solve the case.

Stottlemeyer tries to find proof against the man who framed Monk, and Natalie may ruin everything when she learns the truth.

Heartbroken by the sudden death of Dr. Kroger, Monk rushes into homeownership and gets a little more than he bargained for when he hires a very persistent contractor.

Brilliant chess grandmaster Patrick Kloster's wife Linda Kloster goes to Monk saying that her husband is planning to murder her, and she wants him caught posthumously.

Reese and Finch's latest number is a desperate man near his breaking point. As the case evolves, the duo calls upon a former POI for help, the resourceful and well-connected Zoe.

The Machine identifies a teenager whose brother was just murdered, as the next POI. Meanwhile, Finch grows concerned that The Machine might be discovered.

Murtaugh's witnessing of an alleged abduction and Cole's investigation of a murder begin to collide; Erica's mother comes to town and stirs things up between her, Cole and the case at hand.

Murtaugh realizes his fighting moves aren't as sharp as they used to be when he and Cole investigate the murder of an underground MMA fighter; Trish considers running for public office; Cole and Erica try to keep things casual.

When Cole and Murtaugh investigate a case involving a father and daughter (illegally) crossing the Mexican border, they end up uncovering a major issue with California Boarder Patrol. Meanwhile, Trish prepares her campaign for D.A. and must face parts of her past, before they find their way into the media spotlight. Cole also confronts his past when he experiences flashbacks as a result of an injury.

Sykes does not want a young eyewitness in a gang-related triple homicide to step forward for fear of retaliation. Rusty discusses the case he's investigating with his therapist. Flynn is ready to ask Raydor out on a real date.

Major Crimes discovers that their latest murder victim was a sociopath who made lots of enemies, which makes finding his killer more difficult, as well as pinning a crime on the killer once they find that person.

Cal agrees to testify for the prosecution until he learns that his ex-wife is representing the innocent defendant: a beautiful younger woman accused of killing her much older, and extremely wealthy, husband.

A decorated war hero who is suffering from Post-Traumatic Stress Disorder claims that someone is trying to kill him, and Dr. Lightman is brought in to investigate.

Dr. Lightman allows a wealthy client to shadow him as he tries to find out who critically wounded a Washington, D.C. police officer in an apartment building taken over by drug dealers.

Information about the family murders surfaces as Kyle's memory starts to come back.

Linden and Holder's partnership spirals out of control as they are confronted with the shocking truth behind the Stansbury murders.

Reese and Finch's latest number is a desperate man near his breaking point. As the case evolves, the duo calls upon a former POI for help, the resourceful and well-connected Zoe.

The Machine identifies a teenager whose brother was just murdered, as the next POI. Meanwhile, Finch grows concerned that The Machine might be discovered.

Reese discovers there's more to the story after he infiltrates a smuggling ring to get close to his latest Person of Interest...who may be hiding a secret identity.

Murtaugh's witnessing of an alleged abduction and Cole's investigation of a murder begin to collide; Erica's mother comes to town and stirs things up between her, Cole and the case at hand.