An old friend from Lightman's past comes for help, and gets Lightman involved with a dangerous man being investigated by the FBI. Meanwhile, the rest of the team tries to find the high schooler behind a dangerous and threatening video.

Harry and Fergus take on a disturbing case - a serial killer targeting random victims and leaving a coin in their mouths. Meanwhile, Harry B asks a reluctant Harry to travel the world and Fergus plans to attend college with Lola.

Harry and Fergus travel to the convent of a silent order of nuns after an old friend asks Harry to investigate a suspicious suicide, believing foul play is afoot. Elsewhere, a familiar face provides a very welcome surprise.

A fun day at the races for Harry and Fergus ends in tragedy when a racehorse throws a jockey from the saddle. Harry B discovers the horse was sabotaged and insists the owner, his father, Duncan, is responsible for the crime.

The parents try to find a solution to PRIDE’s problem, and the kids grapple with a new discovery that yields more questions than answers.

After their not-so-fearless leader is taken, our kids spring into action. Alex discovers long-buried secrets about his dad, as the kids uncover new truths about themselves.

With Voight suspended, Antonio takes charge of Intelligence to deal with overdoses of bad heroin, but Ruzek undermines his authority.

Intelligence hunts down the man responsible for the high-rise fire and the case gets personal for Halstead.

The team tries to rescue a teenage girl kidnapped by robbers; Voight and Platt attempt to clear Olinsky's name.

Monk obsesses about a woman he bumped into on the street and the resulting insomnia causes him to witness a crime that apparently didn't occur.

Monk's less than holiday mood is only worsened when he's accused of shooting Santa and becomes the most hated man in the city.

When the Machine produces the social security number of a judge renowned for his tough sentencing, Reese and Finch have the added challenge of investigating a person of interest who wants nothing to do with their brand of vigilante justice.

Reese finds himself captivated by their latest Person of Interest, a beautiful, shrewd and remarkably resourceful woman adept at problem solving.

The Machine identifies a school teacher who witnessed a mob hit as their next POI. Now, Reese and Finch protect the unfortunate soul who was in the wrong place at the wrong time.

Cole and Murtaugh look back on past mistakes as Leo Getz returns as the attorney on their latest case.

Murtaugh and Cole investigate after a robbery of a truck filled with fine art. Cole deals with lingering feelings for Natalie after a development in her life. Meanwhile, Riana blackmails Murtaugh into letting her go to a concert after she catches him in a lie he told Trish.

The body of a dead teenage autistic girl is found in the bed of a registered sex offender's truck, but he claims to be innocent. Meanwhile, Rusty is spooked by the latest development in the Stroh case.

Sanchez becomes a person of interest in a murder investigation when his mother's home caregiver is found dead hours after getting in a fight with Sanchez.

Phillip Stroh claims to have information about three future murders and wants to make a deal with the District Attorney's office; however, part of the deal includes a private one-on-one interview with Rusty.

Agent Reynolds refuses to testify in an undercover case from his past because it may reveal that he killed a man during the operation, but Dr. Lightman tries to come to his defense and keep him out of harm's way.

Dr. Lightman and Dr. Foster help an angry teen find his birth parents, while Eli and Ria try to figure out who was responsible for a fatal "Black Friday" trampling incident at an electronics store.

The hunt for a pornographer leads to a shocking revelation; Holder looks for a scapegoat; Twitch and Lyric find their dream home.

Sarah copes with the consequences of past mistakes; Holder wrestles personal demons; Seward is truthful.

Sarah seeks peace; the detectives pick up a new case; Sarah risks her life when a loved one goes missing.

Reese finds himself captivated by their latest Person of Interest, a beautiful, shrewd and remarkably resourceful woman adept at problem solving.

The Machine identifies a school teacher who witnessed a mob hit as their next POI. Now, Reese and Finch protect the unfortunate soul who was in the wrong place at the wrong time.

Cole and Murtaugh try to balance their family lives with their efforts to bust a gang running a lottery scam.

Cole and Murtaugh look back on past mistakes as Leo Getz returns as the attorney on their latest case.

Murtaugh and Cole investigate after a robbery of a truck filled with fine art. Cole deals with lingering feelings for Natalie after a development in her life. Meanwhile, Riana blackmails Murtaugh into letting her go to a concert after she catches him in a lie he told Trish.