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.

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.

After Damien's body is burned, Laura needs Harry to clear her of murder. Harry and Fergus investigate a murky family history of whiskey and sabotage.

Marcus fears dying while playing Macbeth after three fatal past performances. When Fergus nearly dies onstage, Harry investigates the theatre's dark history.

Scholarship student Derek is accused of killing his principal. Harry goes undercover at St Barts to find who framed him, uncovering disturbing darkness at the school.

Topher helps the kids break into school, but the plan is blown when Dale and Stacey trigger an earthquake. Jonah’s body continues to break down as he leads Karolina into the hole.

When the kids discover that Topher may be more dangerous than they could have imagined, will they help him or will they turn their backs on their new friend?

An investigation into the death of a well known district attorney puts the Intelligence Division at odds with a mayoral candidate. Antonio returns to work but doesn't trust his own judgment when an operation goes sideways.

While chasing a heroin supplier, CPD crosses paths with a convicted criminal recently released on a technicality. Halstead's history with the man threatens the team's ability to put him back in prison.

Atwater goes undercover to bring down the longtime head of a criminal enterprise and becomes entangled in a situation that tests his allegiances as well as his conscience.

Adrian finds himself short an assistant when Natalie is hired to replace the local lotto girl after she's murdered.

A boxer narrowly avoids a bomb, and Stottlemeyer believes it won't be the only attempt with a championship bout coming up. Meantime, Monk splits his time between the case and contemplating retirement when he finds he must pass a fitness exam.

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.

The Machine leads Reese and Finch to Wall Street when a sharp young trader at a major investment bank becomes embroiled in a multi-million dollar financial scam.

Reese and Finch puzzle over how a six-month-old baby could be their next person of interest, but consequently resort to overprotective parenting with an arsenal at their disposal.

Against Murtaugh's advice, Cole reaches out to Tom Barnes to help with a case that hits close to home, putting Murtaugh and Cole's partnership to the test. Meanwhile, Trish prepares to announce her campaign for District Attorney.

Cole is investigated by the FBI, forcing Murtaugh to question his loyalty to his own partner; Cole works a case that puts Natalie's fiance into the cross-hairs right before their wedding day.

Two LAPD officers are killed, and Major Crimes needs to find the lone witness to the crime - an El Salvadoran involved in a counterfeiting ring who was being brought in by the officers.

Major Crimes is paired up with an obnoxious FBI Agent on a kidnapping case from two years ago. Rusty continues his investigation on Alice Herrera.

The viral video of a fatally stabbed man leads to the discovery of several other bodies by a screwdriver serial killer. Gustavo wants help finding his surviving sister but remains guarded against giving out much information.

Dr. Lightman helps Torres's half-sister, who is serving time in a juvenile facility, after an fellow inmate who asks for her help is killed. However, Torres is not convinced that her sister can be trusted.

The Lightman Group discovers that a governor's staffer who was killed during a rally right before the election may have been the target all along to protect a cover-up, and Clara might be lying to protect somebody on the inside.

A young woman is thrust into the world of old money and deadly secrets after accepting a nanny job from a handsome widower.

While bonding with the other nannies, Elena learns that the Wards' previous nanny vanished without warning. Elena continues her search of The Greybourne and discovers a shocking truth.

Elena snoops around Torys apartment while helping Darcy and Bennet, which leads to an unexpected discovery in the secret room. Elena is rattled by a surprise call from her past.

The Machine leads Reese and Finch to Wall Street when a sharp young trader at a major investment bank becomes embroiled in a multi-million dollar financial scam.

Reese and Finch puzzle over how a six-month-old baby could be their next person of interest, but consequently resort to overprotective parenting with an arsenal at their disposal.

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.

Against Murtaugh's advice, Cole reaches out to Tom Barnes to help with a case that hits close to home, putting Murtaugh and Cole's partnership to the test. Meanwhile, Trish prepares to announce her campaign for District Attorney.