Chicago P.D.

When a young bystander is shot during a difficult operation, the top brass question Halstead's involvement.

A Chicago police officer becomes a suspect in a deadly terrorist attack.

An investigation into the murder of an illegal immigrant is plagued with roadblocks as Intelligence contends with the perception of the police among the city's immigrant population.

A series of murders hits close to home for Atwater.

A smuggling ring preys on foreign adoptees.

Upton must work with a vice cop she dislikes to help intelligence crack a drug related murder.

Halstead goes undercover to stop an ex-military kidnapping crew from killing an innocent child.

Intelligence investigates a twisted case involving a congressman caught with a dead girl.

Intelligence works to take down an opioid ring after the daughter of a prominent judge dies of an overdose.

Halstead puts his credibility and career on the line to help solve a case with ties to his new girlfriend.

Burgess works with her first criminal informant to track down a ruthless pimp and break up his prostitution ring.

Atwater goes missing and the team digs into his past to discover why he's been taken.

When a gang from El Salvador infiltrates Chicago, Intelligence works with a visiting detective to put an end to the crew's brutal tactics.

Intelligence investigates the death of a college athlete killed after kneeling in protest.

Intelligence tracks down a vigilante killing rapists. The investigation hits home for Burgess (Marina Squerciati), who begins to question if the men who attacked her sister truly paid for their actions.

Intelligence investigates a string of bombings targeting members of the media. Racing against a ticking clock, the team enlists Firehouse 51 to help examine the devices and prevent the next attack.

When a prominent Alderman known for his urban revitalization efforts is killed, Intelligence looks into the corruption haunting his neighborhood. Meanwhile Olinsky (Elias Koteas) feels pressure after receiving an ultimatum from Woods (guest star Mykelti Williamson)

Upton (Tracy Spiridakos) brings back an old undercover identity to help take down a meth ring spearheaded by a former criminal contact.

A string of stash house robberies lead back to an unlikely individual.

After Voight (Jason Beghe) witnesses the kidnapping of a young woman with a mysterious connection to his past, Intelligence works to find a connection between her kidnapping and several bank robberies.

Halstead (Jesse Lee Soffer) and Atwater (LaRoyce Hawkins) go undercover to prevent military grade weapons from hitting the street.

Tensions run high as Intelligence seeks justice for Olinsky (Elias Koteas) after he's stabbed in prison.

Get prepped for Season 5 with this deleted scene from S4 - in which Lindsay and Halstead confront the distance between them.