Voight and team head to a house that’s been associated with a number of top gangs. Events at the search result in Ruzek, being encouraged to seek some counseling which may have lasting repercussions professionally and personally. Meanwhile Halstead’s temper rises when he comes in contact with some unwelcomed people from his past.

Halstead's badge is revoked when Lonnie Rodiger is found dead; Severide and Clarke find Dr. Elliot's torso; Sumner tries to prove herself; Lindsay shares a moment with Severide.

The Intelligence Unit works to find the bombers. Even with government agencies in the mix, Voight and his team work the case from their own angles and connections. Lindsay and Antonio question doctors who handled the transplant surgery for an Ambassador from Syria, but no clues emerge. Olinsky gets some solid intel and the team work from there. It’s a race against time as they realize there may be additional bombs targeted to detonate. Meanwhile Burgess sits vigil for her niece whose life hangs in the balance.

The crossover starts on Chicago Fire S02E20 A Dark Day (I).

Burgess gives chase after Roman is wounded by a hooded perp who opened fire on their patrol car and shoots who she thinks is the suspect, but no gun is found at the scene—and the person she shot is a 17-year-old honor student.

Severide is brought into the District for questioning after his car is found to have caused a deadly crash. As the investigation gets underway, the team works to uncover a group of car-jackers who may be the key to Severide's innocence.

The crossover starts on Chicago Fire S05E09 Some Make It, Some Don't (I).

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.

The crossover continues on Chicago Fire S06E013 Hiding Not Seeking (II).

Using information from Chicago Fire's Cruz, Intelligence chases down the robbery crew that’s been using the lockbox key. Voight is under pressure to bring the crew to justice without tarnishing the reputation of a murdered firefighter who might have been involved.

The crossover starts on Chicago Fire S07E15 What I Saw (I).

After zeroing in on the suspect responsible for the bioterrorism that’s gripping Chicago, the PD prepares to undertake their biggest manhunt yet. Upton is torn between helping track down the perp and providing emotional support to the scared young girl that needs her. Voight fears his team is being sent on a wild goose chase.

The crossover starts on Chicago Fire S08E04 Infection (I) and Chicago Med S05E04 Infection, Part II (II).

Intelligence searches for the dealer who caused multiple overdoses and is connected to Roman's missing sister. The case becomes a homicide investigation when they find the dealer's dead body.

The crossover starts on Chicago Fire S08E15 Off the Grid (I).