The team members attempt to recover a 5-year-old boy, Ethan Heller, who was in the back seat of his family's SUV when it was apparently carjacked.

The team members search for Rachel, an agoraphobic advice columnist who had not left her apartment in 2 years.

Nikita goes to London with Owen to retrieve one of Percy's black boxes; there, the two disagree about what to do with it.

The holiday cheer is interrupted.

After gangsters open fire in a crowded club, tensions rise between Sal and Gil on the gang task force. And Sammy confronts his wife about crossing the line too often.

The Southland officers are sent out to capture a rapist impersonating a cop. While Lydia's reunited with her former partner, Russell, Sal's secret affair is revealed to his wife.

Patrick Jane must deal with two failed robbery attempts: one resulting in the murder of a repair shop owner and the other involving a former suspect personally hired by Jane to break into LaRoche's home.

Nikita goes to London with Owen to retrieve one of Percy's black boxes; there, the two disagree about what to do with it.

Stabler goes undercover as a big rig driver to expose an international smuggling ring; as he settles into his new identity, he gets to know the "working girls" and a pattern of disappearances emerges.

The holiday cheer is interrupted.

The Southland officers are sent out to capture a rapist impersonating a cop. While Lydia's reunited with her former partner, Russell, Sal's secret affair is revealed to his wife.

Patrick Jane must deal with two failed robbery attempts: one resulting in the murder of a repair shop owner and the other involving a former suspect personally hired by Jane to break into LaRoche's home.

While investigating the disappearance of Leah Robinson, the team begins to suspect that she may not be as innocent as her husband and minister think she is.

The team members attempt to recover a 5-year-old boy, Ethan Heller, who was in the back seat of his family's SUV when it was apparently carjacked.

The team members search for Rachel, an agoraphobic advice columnist who had not left her apartment in 2 years.

The holiday cheer is interrupted.

The Southland officers are sent out to capture a rapist impersonating a cop. While Lydia's reunited with her former partner, Russell, Sal's secret affair is revealed to his wife.

Patrick Jane must deal with two failed robbery attempts: one resulting in the murder of a repair shop owner and the other involving a former suspect personally hired by Jane to break into LaRoche's home.

Nikita goes to London with Owen to retrieve one of Percy's black boxes; there, the two disagree about what to do with it.

On Christmas Eve in a quiet town, elderly couple Bob and Idella Young are brutally slain at home.

Herrmann investigates the rise in missing fire hydrants and teams up with Kylie to track them down. Kidd's cousin comes to town, revealing surprising family history.

After a daring rescue at an adventure park, Kidd asks Severide to create a ropes course for Girls on Fire. Violet's former nemesis returns, pleading for her help. Herrmann creates a signature cocktail for Molly's.

An English professor lays out a stirring hoax theory on America’s most famous cold case, launching filmmaker Andrew Nock on a journey into the world of "The Zodiac"; victims' family members talk on camera for the first time.

As events in the hotel near their explosive climax, with many still in danger, Jo fights to save lives, protect her family and stop the shooters.

When a prison guard is stabbed to death outside of a jewellery store, Patrick Jane suspects one of the guard's inmates is the killer. Meanwhile, Rigsby questions his own father about the murder.

After a daring rescue at an adventure park, Kidd asks Severide to create a ropes course for Girls on Fire. Violet's former nemesis returns, pleading for her help. Herrmann creates a signature cocktail for Molly's.

Ciro's turn hasn’t come quite yet for Pietro manages to hold on to the reins from inside the prison, even sending Ciro and his men to eliminate the Nigerian crack-dealers in a brutal massacre. Elsewhere, Genny continues in his attempts to woo Noemi.

With Pietro gone, it is Imma who surprisingly starts to take care of business. Ciro is left with no choice but to take his orders from her now. When Pietro informs her that Genny and Ciro are to be his heirs, Imma doesn't hesitate to send them off on dangerous missions.