The matron of honour is poisoned at a bachelorette party even though all the others were sharing the same bottle of champagne. Harry and Fergus try to figure out how she was poisoned.

The Runaways become suspicious of one another with a traitor among them. Catherine takes responsibility for her past. Leslie seeks help protecting the child growing inside her.

Disher inherits his uncle's farm and invites Monk to visit him when he suspects that his uncle's death was not really an accident.

Murtaugh and Riggs search for the culprit of a local jewelry heist; Murtaugh gets called "grandpa" by another parent while at the playground with Harper sending him into a tizzy; Riggs deals with withdrawal from drinking.

Dex goes undercover as a potential buyer to help Hoffman and Grey with the next phase of their drug case. Meanwhile, Dex unexpectedly becomes close to a fellow veteran support group member and soon discovers they have more in common than they thought.

A homeless teenage girl is found dead in a garbage can in an upscale neighborhood, and Sharon's husband comes to hear a proposal.

Intelligence works with a visiting detective to take down a gang from El Salvador that has infiltrated Chicago.

Dr. Lightman and Torres investigate a spate of suicides in young Indian women. We discover that a suicide has helped shape Dr. Lightman. Meanwhile, Dr. Foster and Loker are at odds while they investigate a case of suspected SEC fraud.

The matron of honour is poisoned at a bachelorette party even though all the others were sharing the same bottle of champagne. Harry and Fergus try to figure out how she was poisoned.

Dex goes undercover as a potential buyer to help Hoffman and Grey with the next phase of their drug case. Meanwhile, Dex unexpectedly becomes close to a fellow veteran support group member and soon discovers they have more in common than they thought.

Disher inherits his uncle's farm and invites Monk to visit him when he suspects that his uncle's death was not really an accident.

Intelligence works with a visiting detective to take down a gang from El Salvador that has infiltrated Chicago.

Dr. Lightman and Torres investigate a spate of suicides in young Indian women. We discover that a suicide has helped shape Dr. Lightman. Meanwhile, Dr. Foster and Loker are at odds while they investigate a case of suspected SEC fraud.

Murtaugh and Riggs search for the culprit of a local jewelry heist; Murtaugh gets called "grandpa" by another parent while at the playground with Harper sending him into a tizzy; Riggs deals with withdrawal from drinking.

The kids search for Leslie and Alien Alex. Meanwhile, Leslie gives birth and Xavin fulfills her prophecy. The kids go head to head in a final battle against the aliens.

A man from Orla's past begs for her help: Ben Finnegan is on the run from the police, framed for murder, and being hunted by a killer with a crossbow. The only person Orla can turn to is the last one she ever wants to ask for help - Harry.

A street musician is murdered six different ways and the killer is threatening to strike again, but Monk and his colleagues are forced to the sidelines by obnoxious FBI agents.

An elderly married couple, killed execution-style in their home, with their daughter and grandchildren missing, leaves a joint task force to suppose that they may be hostages.

Dr. Lightman and Dr. Foster help FEMA run a rescue operation on a collapsed construction site. Torres and Loker talk to the girlfriend of an internet billionaire.

Dex is hired to investigate a bride's fiancé after suspicions arise regarding the motives behind the hurried nuptials. Dex asks Hoffman for help with the case and discovers there's more to this couple than meets the eye.

After the city's gun buy-back program is robbed, the team is on a hunt for those responsible. Meanwhile, Murtaugh walks on thin ice with Trish, Riggs finds an unlikely friend in Ruthie, and Captain Avery is reunited with a college "frenemy" who has key information about the case.

Intelligence investigates the murder of a basketball player following an anti-police rally and the case gets complicated when Woods' daughter gets involved.

Linden and Holder finally find out who murdered Rosie Larsen.

An elderly married couple, killed execution-style in their home, with their daughter and grandchildren missing, leaves a joint task force to suppose that they may be hostages.

Dex is hired to investigate a bride's fiancé after suspicions arise regarding the motives behind the hurried nuptials. Dex asks Hoffman for help with the case and discovers there's more to this couple than meets the eye.

Dr. Lightman and Dr. Foster help FEMA run a rescue operation on a collapsed construction site. Torres and Loker talk to the girlfriend of an internet billionaire.

After the city's gun buy-back program is robbed, the team is on a hunt for those responsible. Meanwhile, Murtaugh walks on thin ice with Trish, Riggs finds an unlikely friend in Ruthie, and Captain Avery is reunited with a college "frenemy" who has key information about the case.