Chicago P.D.

Atwater reunites with an old friend from his academy days after a bombing rocks downtown Chicago.

A string of violent robberies across the city digs up one family's secrets; a surprising detail of Voight's past resurfaces.

A desperate man searching for his daughter holds a member of the team hostage; Voight learns about the accusations Bunny made regarding a case from his past; Antonio finds out that Olinsky has been keeping a secret.

Voight and the team help retired Cmdr. Perry extract his nephew from a corrupt unit; Lindsay struggles to stay clean; a woman from Olinsky's past contacts him.

Intelligence pursues heroin kingpin Derek Keyes; Lindsay's downward spiral continues; Olinsky tells Platt about a secret from his past; Roman talks to Burgess about his concerns regarding Ruzek.

Roman and Burgess discover the corpse of a young boy who was reported missing; Burgess talks to Ruzek about Roman's suspicious behavior; Bunny plans to make a statement that could impact Voight's career.

A mass shooting takes place in an athletic club; Atwater deals with his new assignment; Halstead and Platt try to check up on Lindsay.

After arriving in Chicago to assist Voight and the team with a rape/murder case that has distinct similarities to a decade-old case from New York, Sgt. Benson asks Fin and Amaro to help; the prime suspect asks for a meeting with Lindsay.

Still struggling with a loss, the team must put feelings aside when a cafe is bombed; Atwater winds up in hot water after making a mistake.

Intelligence searches for a missing teen who they believe poses a threat to students at his school; Atwater wants to make a good impression on a police captain.

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

Voight and Chapman work together to uncover Deputy Chief Reid's shadow dealings as Reid assigns Intelligence to a carjacking case.

When Intelligence follows up on a tip about an upcoming drug trade, the team discovers a man's mutilated body; Burgess helps plan a surprise for Platt.

Cook turns to her family when Intelligence faces administrative roadblocks that threaten a kidnapping investigation.

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

With the suspects still at large and conditions worsening underground, first responders race against the clock to reach the trapped victims, while the investigation into the assailants comes into focus.

A teenage girl is violated during a home invasion; Voight helps a former acquaintance; Platt and Mouch receive upsetting news regarding their upcoming wedding.

Voight wants to make his former cellmate a confidential informant as the unit tries to take down a big cocaine supplier and local dealers; Burgess makes a decision about her relationship with Ruzek; Roman works with Firehouse 51 to fund a wedding.

Ruzek grapples with his father's worsening condition while Intelligence searches for an elusive serial killer.

Cook works with a confidential informant for the first time in a robbery-murder case with links to a star college athlete.

A decapitated corpse found in Lake Michigan is connected to Voight's social circle; Roman makes a grave error; Antonio makes a decision that could impact Michelle's future -- without consulting Olinsky.

A doctor connected to Voight is investigated after four patients with chemo overdoses are sent to Chicago Med; Platt and Burgess work to clear Roman's name.

The showdown with Deputy Chief Reid intensifies when Intelligence narrows in on Otero.

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

A mounting street war threatens a community-center project that Atwater is trying to get off the ground.

Intelligence makes a gruesome discovery that leads Torres to go undercover at the juvenile detention center where he served time as a teen.

The search for the suspect in a shooting uncovers a surprising personal connection to Atwater and Val, raising questions about their relationship status.

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.

Ruzek's future with the unit is in question after a botched undercover job; a corpse is discovered in an SUV; Lindsay and Halstead move forward with their relationship.

An unexpected visitor causes disruption for Ruzek and Burgess amidst an emotional investigation involving an unidentified young girl.

An investigation into a drug robbery gone wrong reveals Voight has ties to a teen linked to a double murder; Desk Sgt. Platt cares for a young girl.

A case involving one of Chicago's most wanted fugitives hits close to home with Olinsky; an altercation with another officer lands Sean Roman in hot water; Platt helps Nadia prepare for her polygraph test.

Voight believes the man who tried to kill him is someone he and Olinsky once put away; Atwater unintentionally spills information about Ruzek's history that disturbs Burgess.

Voight pulls Darius in after Crawford asks intelligence to investigate a dangerous drug, but there is little trust in the relationship; when a plan to nail a dealer goes awry, the team must make a tough decision about Darius.

Voight makes a deal with Darius Walker to help bring down a rogue group of dirty cops dealing drugs that were supposed to be destroyed; Upton clashes with Voight and enacts her own form of justice.

Antonio and his sister talk to Elliot Gish about the person they think is responsible for the fire that killed Shay; Lindsay has second thoughts about the task force; Platt's new, sunny demeanor results in curiosity.

Ruzek's father (Jack Coleman) is first on the scene of a double murder; Lindsay prepares for an undercover investigation in Bolivia; Roman and Burgess try to move forward.

Bunny comes to Lindsay with a concern that leads the team to a case that robbery-homicide has been investigating; Voight is suspicious of Bunny's motives.

Olinsky goes under cover as a hit man for hire after Lindsay is tipped off about a grieving father looking to avenge his daughter's death; when Ruzek returns from his undercover assignment, Voight puts him on patrol duty.

When the crushed body of a young teen who ran away from a treatment center for troubled girls is found in an abandoned building, Voight sends Halstead under cover as a guard to investigate the center from the inside.

A priest and parishioners block law enforcement from entering a church where two murder suspects are suspected of hiding; Rixton is caught in a lie with Voight.

The members of intelligence go under cover at a World Trade conference to assess political threats; Halstead's brother immediately stirs up trouble when he shows up in town.

The team investigates a home explosion that left a charred body, one injured survivor and no witnesses; Lindsay and Halstead receive a strange warning about Rixton.

As Voight and his team search for the bombers, they realize there might be more bombs set to detonate; Burgess' niece fights for her life.

Atwater settles into his new role; Lindsay turns to Voight for help; Jin is confronted about his meetings with Stillwell.

As the Sheldon Jin investigation moves forward, Internal Affairs keeps a close eye on Voight; Voight's vehicle is T-boned while following an armored car carrying Ruzek; Burgess meets her new partner; Lindsay visits her mom.

Several murder victims are found with a dollar bill pinned to their chests; Voight makes a discovery about a friend; a series of home invasions.

Cmdr. Perry notifies the unit that Pulpo has been released to help with a case; Ruzek gets difficult news; when a bit of Lindsay's past resurfaces, Voight reminds her how far she's come.

Platt and Voight discuss their pasts; Jin uses a scapegoat when he is caught tinkering with Voight's computer; Lindsay realizes she needs to come clean.

Ruzek's future with the unit is in question after a botched undercover job; a corpse is discovered in an SUV; Lindsay and Halstead move forward with their relationship.

Burgess and Atwater come across a gunshot victim and the only witness is Olinsky's daughter; Ruzek goes to Burgess for help with an undercover mission.

Voight is attacked and abducted while trying to help Olive; Roman and Burgess search for a girl who has taken off with a police badge.

Halstead's badge is revoked when Lonnie Rodiger is found dead; Severide (Taylor Kinney) and Clarke (Peter Mills) find Dr. Elliot's torso; Sumner (Sydney Tamiia Poitier) tries to prove herself; Lindsay shares a moment with Severide.

The team races against the clock when two teenage girls disappear; Voight seeks honest answers from the father of one of the girls.

Voight's new Internal Affairs handler proves to be suspicious of his actions; Voight must work with his former partner from the Gang Unit; Halsted enlists Jin to help him gather more information on Lonnie Rodiger; Olinsky takes Ruzek down a peg.

Ruzek and Atwater go under cover as prison inmates in order to find the man they believe killed a 10-year-old girl; Burgess and Roman give a tour of the district to some boys they believe are part of the Police Explorers program.

When a bartender takes a bullet intended for Halstead, the bounty on him becomes more real; following a tense interaction, Platt and Nadia reach an understanding.

Dueling gangs are suspected when a massacre occurs and $8 million is stolen; Platt asks Ruzek for help.