A car plows through a crowd outside of a concert venue and is followed by gunfire, sparking fears that it may be terror-related. Burgess spots Atwater's brother where he shouldn't be. The team works to bring peace to the community before more blood is shed.

When a young officer is shot dead in the lobby of an apartment building, Intelligence looks to the latest known offenders who have threatened the police. But when a second officer is killed, the team finds that they are dealing with someone who is highly trained and knowledgeable.

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 Chicago's "Night Crawler" Bobby Trent is murdered over a single piece of mysterious footage, Intelligence must investigate one of Chicago's wealthiest families. Meanwhile, Burgess's sister Nicole arrives at the District for a visit, and presents an icy attitude towards Ruzek.

In the wake of several gang-related child abductions, Intelligence must race against time to find a kidnapped boy. Owing to their swiftness and military precision, the team scours the VA records and tracks the suspects to a former Army Ranger. With his previous experience as a Ranger, Halstead convinces Voight to send him undercover to try and get information from inside.

Halstead's partying with Camila unintentionally puts him in the middle of a drug-related homicide. He's forced to choose between loyalty to his unit and his girl. Meanwhile, Voight finally discovers the mole in his unit.

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).

After Voight 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. Ruzek gets a tip that a grand jury has been summoned, putting Olinsky one step closer to standing trial for Bingham’s murder.

Voight and Ruzek lock horns over how to handle the aftermath of the Antonio situation. Meanwhile, a series of violent carjackings turns deadly, and Ruzek must rely on a C.I. he grew up with to help solve the case.

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).

With the threat of a gang war looming, Voight and Ray Price must organize a peace summit to end the bloodshed before more innocent people get hurt. Burgess evaluates her future with Blair.

Intelligence's investigation into the murder of Burgess' boyfriend threatens to reveal a dark side she was unaware of. The real motivation for his murder uncovers a much more unsettling truth.

Voight pulls Darius in after Crawford asks Intelligence to investigate a dangerous drug, but there is little trust in the relationship. When their plan to nail a dealer goes awry and another CI is murdered, the team must make a tough decision about Darius.

When the son of an influential former officer is implicated in a murder, Moore pressures Voight to charge him quickly. The stakes are raised in Atwater's fight against the blue wall after patrol officers stop responding to his team's calls.

Ruzek and Burgess discover a child walking alone in the middle of the street, and when they take her home, they discover that her entire family has been murdered. Upton is approached with a job offer from the FBI.

The team investigates a rash of car jackings and finds the truth is more complicated than they realize. Burgess makes a discovery about a previous case that will change her life forever.

Ruzek and Atwater are tasked with making an arrest after a high-profile shooting. The situation becomes complicated when it's clear someone doesn't want them to make it back to the station.

A wellness check on a family reveals signs of foul play and Upton is determined to find the parents and young daughter. As Hailey delves further into the troubled family dynamics, she finds herself reflecting on her own childhood trauma.

Voight and the team pursue a ruthless crime ring whose business has hit close to home. As they dig deeper, the extent of the danger becomes more apparent. Deputy Superintendent Samantha Miller second-guesses her decisions.

Voight and the team muster all their expertise to bring down a deadly crime ring. Burgess finds herself in a dangerous situation.

When a P.D. informant is murdered, the team digs in to track down the perpetrator only to learn a shocking truth. Voight and Ruzek strategize to help Burgess.

When Upton and Ruzek answer an emergency call to an abandoned house, their investigation leads them down a dark path.

With the FBI closing in on the Roy Walton investigation, Voight and Halstead strategize on a way out. After a city bus driver is shot by a passenger, the team investigates a possible abduction.

While out for a jog, Upton witnesses a horrible car crash and risks her own life to save the passengers. After learning more about the victims, the team must track down the man responsible for the brutal crash.

When a young man is shot outside the Cárabo Bakery, the team works to connect the shooting to bakery owner Javier Escano, who has been under surveillance. Despite the increasing danger, Voight helps informant Anna Avalos get even closer to their target.

Voight and the team delve into a cold case in search of clues to solve a shocking new crime. With its focus on buried memories, the case sparks concern for Burgess and Ruzek about Makayla's mental healing.

After an explosion rocks the case, the team scrambles to finally take down Escano as everyone nears their breaking point.

Still reeling from the death of informant Anna, Voight faces a new threat as he tries to keep the neighborhood clean. New wrinkles develop in the Upton, Halstead and Voight dynamic. The team gets a new chief.

Upton's dogged pursuit of a missing teenage girl leads the team into a dark web of human trafficking. Chief O'Neal becomes involved with the unit's investigation when it becomes evident his son, Sean, has a connection to the missing girl.

After a shocking discovery, the team begins closing in on Sean O’Neal with every shred of evidence they can find. Determined to keep his son out of prison, Chief O’Neal hires a lawyer.

After a brutal shooting, Burgess and Ruzek find themselves trapped aboard the busy "L" subway. As they piece together scant evidence, the team is drawn into a dark family drama.

When a family is poisoned in their home, the team discovers a connection to the Becks. Ruzek goes undercover to work for their business, and as he gets closer to Samantha, chilling information about her father, Richard, comes to light.

Tasked with shadowing a crisis prevention team, Upton finds her approach to policing at odds with the team's mental health clinician. Voight stands by Upton as she continues to struggle in her personal life.

Upton becomes consumed with a decades-old missing persons case linked to Petrovic after a young child shows up to the district seeking help.

Intelligence chases down a lead in the ongoing serial killer investigation as news of the case reaches the public.

A month after Voight's close brush with death, Intelligence is overwhelmed with cases as they catch a high-stakes drug bust.

In the midst of a momentous rainstorm, Intelligence lends support to Officer Cook when she and her partner disagree about an investigation.

The unit learns the truth about a secret Torres has been keeping, as Deputy Chief Charlie Reid puts a focus on Intelligence.

Voight questions Deputy Chief Reid's motives in enacting a Violence Reduction Initiative across a neighborhood where numerous gangs are fighting for territory.

Burgess' memory recall is put to the test following a deadly incident at her local diner.

Ruzek witnesses a tragic accident on an icy bridge, leading Intelligence into a dark, sinister case involving sex trafficking.

Forced to cease operations while under investigation by Internal Affairs, Intelligence goes off-book to bring down Reid once and for all. Ruzek and Burgess consider delaying their nuptials amid the uncertainty.