Chicago P.D. - Season 4 (2016)

Intelligence investigates a shooting outside a concert that leads to a tangled web of gang-related violence.

Intelligence tracks down the people who have been dealing a drug that's been linked to several overdoses throughout Chicago.

A teenage girl is found dead in the home of a baseball player who's a friend of Olinsky's.

The only witness in the case against a suspected serial rapist is found murdered.

A highly trained killer declares war on the Chicago police department.

Kelly Severide of Firehouse 51 is brought to the District for questioning when his car is found to have caused a deadly crash, so the team tracks down a group of carjackers that may prove Severide's innocence.

When the body of a young woman is found, the Chicago police realize there's a serial killer at large after comparing her case with others.

When a mutilated sex offender is found dead, it is unclear if he was the victim of a hate crime, sexual assault or self-mutilation. As Intelligence questions those related to the case, they find themselves up against a private "special police" force who may be covering up illegal activities. Meanwhile, Halstead runs Jimmy's DNA to confirm that he is actually Lindsay's father.

The investigation of a jogger's murder in the park is blocked by a church offering sanctuary to the prime suspects.

The body of a 15-year-old girl is found crushed in an abandoned building after she runs away from a treatment center for troubled girls. Voight sends Halstead undercover as a guard to work from the inside at the center, where he believes the girls are trading sexual favors for something in return.

When a charred body is found in a torched house along with an injured boy, Intelligence works to find the cause.

Intelligence re-opens a case when a grieving father seeks to avenge his daughter's murder.

Intelligence works to find the arsonist behind a warehouse fire that left Olinsky's daughter fighting for her life.

A hiker leads intelligence to a woman being held hostage in the woods outside Chicago.

Intelligence investigates one of Chicago's wealthiest families when "Night Crawler" Bobby Trent is murdered.

Burgess's sister becomes a sexual assault victim after she's encouraged to spend a night out with friends.

Voight uncovers a connection between the murder of a teenage boy and a 17-year-old case.

Intelligence uncovers a surprising crew of suspects in a series of bank robberies.

Intelligence tracks down a group of vigilantes torturing and killing pedophiles.

Lindsay deals with the consequences of her actions when her mother is suspected of murder.