Intelligence is in pursuit of Derek Keyes, number one on Chicago's Most Wanted list and heroin kingpin. Meanwhile, Halstead tries to get through to Lindsay as her downward spiral continues after her three-week absence from the unit. At District, Olinsky opens up to Platt about a secret from his past. Roman expresses his concerns to Burgess about what she's getting into by marrying Ruzek.
While pursuing a gangbanger, Burgess and Roman come across the body of an eight-year-old boy who was reported missing. Intelligence launches an investigation to find the hugger and Antonio and Lindsay question a prime suspect. Meanwhile, Burgess confides in Ruzek about Roman's suspicious behavior and Bunny heads to the Ivory Tower with a statement that could be detrimental to Voight's career.
While Platt tries to manage a chaotic desk area, a man struggling to get her attention takes a drastic action and demands that the unit find his missing daughter. Commander Fischer informs Voight that Bunny is bringing up new accusations on a case from his past. Lindsay urges her mother to fix the situation. Antonio is shocked to learn a secret Olinksy has been keeping.
After surviving a hit against him, Voight is convinced the culprit is a criminal he and Olinksy once put away and is determined to catch him before he injures anyone else. Atwater accidentally spills information about Ruzek's past which unsettles Burgess. Platt assigns Burgess and Roman a high society dognapping case.
After a botched undercover job, Ruzek is under scrutiny by the new Street Deputy Crowley who will determine his future with the unit. A suspicious person call turns into a hug investigation when Burgess and her temporary partner Price discover the body of a dead man in an SUV.
After Mouse identifies the victim as the owner of a security company, the unit soon realizes there might be more to his story. Halstead and Lindsay take a step forward in their relationship.
Intelligence sets out to find a missing teenaged boy who they believe poses a serious threat to the students at his wealthy school after finding disturbing drawings in his notebook. Meanwhile, Atwater is eager to make a good impression on a prominent African American police Captain and Olinsky and Michelle find themselves in a difficult situation and turn to Ruzek and Burgess for help.
When Intelligence follows up on a tip Antonio and Halstead received from a reliable informant about an upcoming drug trade, the team is shocked to discover the mutilated body of a man. Upon further investigation, the body is identified as a government official and when Olinksy, Ruzek, Lindsay and Halstead question the man's acquaintances they discover he had access to very important devices. Meanwhile, Burgess helps plan a surprise for Platt.
When the decapitated body of a woman found in Lake Michigan is connected to Voight's social circle, Lindsay fears his relationship with the group may hinder his ability to approach the case objectively. Roman is having a hard time coping with recent events and an error in judgment causes him to make a grave mistake. Meanwhile, Olinsky becomes upset when Antonio doesn't consultant him before making a decision that could affect Michelle's future.
A doctor with personal connections to Voight is under investigation when four of his patients are committed to Chicago Med after an overdose of chemo. The doctor denies Lindsey and Halstead access to his files, but after obtaining a warrant the team is able to track down his patients and discover all of them have been poisoned with unnecessary chemo. Meanwhile, Burgess and Platt work together to clear Roman's name.
(Malignant (1) aired on Chicago Med, season 1, episode 5. The Beating Heart (2) aired on Chicago Fire, season 4, episode 10.).
After a luxury condo is robbed, the team is shocked to learn that not only was the family fast asleep when the crime occurred, but their teenaged daughter was violated during the invasion as well. Voight consults Jimmy from Firehouse 51 to confirm his suspicion that the family was knocked out by a powerful gas, and Lindsay, Halstead, Atwater and Ruzek go undercover to seek out the perpetrators. Meanwhile, Voight tries to help a former acquaintance get back on his feet, and Platt and Mouch receive disappointing news regarding their upcoming wedding.
Voight convinces Deputy Crowley to bring in his former cellmate, Eddie Little, as a CI for the unit in order to help bring down a big-time cocaine supplier and his local dealers. Antonio is skeptical of this decision but Voight puts him at ease when he opens up about his time in prison with Little. Meanwhile, Burgess makes a difficult decision regarding her relationship with Ruzek and Roman devises a plan to help fund Platt and Mouch's wedding with the help of Firehouse 51.
Lindsay goes undercover in an effort to track down a rogue police officer targeting women leaving a local casino. When Detective Martin Watts, who oversees all cases out of the casino, gets word of the investigation he becomes involved much to Voight's dismay. After recent events, Burgess sets plans in motion to transfer Districts pending Platt's approval, and Mouse attempts to lift Ruzek's spirits by offering to set him up with a friend. Meanwhile, Antonio volunteers to take Roman's place in the upcoming boxing match against Jimmy from Firehouse 51.
After infamous criminal Gregory Yates escapes from a New York prison, Lindsay and the team learn that he intends to flee New York and is headed for Chicago. The SVU team informs Intelligence that Yates has been gathering information on Lindsay and after Platt calls in a triple hugging likely at the hand of Yates, Benson and Fin catch the next plane to Chicago. Upon investigation of the crime scene, the team learns that another tenant in the building is missing and they work to find a connection between Yates and the woman.
(Part 2 of a 2-part Law & Order: Special Victims Unit - Chicago P.D. crossover on 2-10.).
While working at a sobriety checkpoint, Burgess finds a duffel bag full of heroin in the truck of a respected college professor who claims to know nothing about how the drugs ended up there. Voight decides to hold off on charging the unlikely suspect, and Olinksy and Antonio follow up on a lead to see who is behind the drug smuggling. At District, Roman expresses his desires to become a Field Training Office to Platt, and Mouse sets Halstead up with an off-duty security job working for the attractive owner of a medical marijuana clinic.
When a young boy is executed, Intelligence turn to the boy's parents for information and upon further investigation, discover the father has a criminal background and was a part of a local gang. After another shooting in gang territory, this time nonfatal, Lindsay and Halstead speak to the victim's mother to see if the two crimes are related and Mouse works to find a connection. To honor the deceased young victim, Antonio, Platt, Roman, Burguess, Mouse and a number of other CPD officers and members of the community come together for a candlelight vigil.
While out on a bank run for his off-duty security job at the dispensary, Halstead and his co-workers find themselves under attack by a unhappy robbery crew which quickly becomes a full-scale shootout. Voight and Lindsay question the owner of the dispensary who mentions her business has received threats from local gangs upset she's cutting into their revenue. Meanwhile Roman, Burgess, Antonio, Halstead, Ruzek and Atwater follow-up on a lead and track down a potential suspect.
While responding to a call of shots fired, Voight, Antonio, Halstead and the team come across a secret battered woman's shelter and discover the owner has been wounded and a resident of the shelter has been kidnapped. The team faces a challenge as the gunman is still at large and the identities of the women are kept confidential. Meanwhile, Burgess and Roman go undercover to track down a man robbing people by catfishing them on a dating app and Lindsay opens up to Halstead about her past.
When a call comes in about a woman stabbing a man then fleeing the scene, Burgess and Lindsay go investigate and find a young woman with the weapon in her hand. The suspect turns out to be a victim and she tells Olinsky that she was held hostage for months and her kidnapper attempted to psychologically manipulate her into forgetting her identity while he physically abused her. The team sets out to find the woman's abductor before he can harm anyone else. Meanwhile, tensions are high at the station when Ruzek accuses Roman of having feelings for Burgess.
Responding to a call about a suspicious duffle bag at the Chicago Lakefront, Voight is horrified to discover that the bag contains the frigid and unmoving body of a newborn baby. Determined to find the culprit who abandoned the infant, Intelligence receives a promising lead based on information provided by Chicago Med and Ruzek helps zero in on a potential suspect. Meanwhile, Voight is surprised to hear that his son is in town and Burgess and Roman grow closer.
After a hooded man open fires on their patrol car, Roman is left wounded and Burgess takes off after the shooter, briefly losing sight of him, and shoots when she relocates him turning in her direction with a glimmer of silver in his hand. No gun has been found at the crime scene and the shooter is identified as a 17-year-old honor student who will likely never walk again due to his injuries. Protests begin as the public views the case as another incidence of a police officer shooting an unarmed African American teenager. Assistant State Attorney Peter Stone (Philip Winchester), the same man who sent Voight to prison, has been assigned to help defend Burgess and conduct his own investigation under the supervision of State Attorney Mark Jefferies (Carl Weathers). Stone and his investigators Daren Okada (Ryan-James Hatanaka) and Lori Nagle (Joelle Carter) need to collect enough evidence to indict the teen and clear Burgess, but must tread with caution on this high profile case as tensions run high.
While responding to a call of shots fired at a family residence, Lindsay and Halstead discover the only survivor is the youngest daughter who is traumatized. While Lindsay and Dr. Charles evaluate the girl and see if she can help identify the hugger, Antonio and Olinsky look into a pyramid scheme "self-help" group for potential suspects. Meanwhile, Platt tries to make the case to Commander Crowley for Burgess and Roman to remain partners.
When the team finds the body of a widowed, single-mother in the trunk of her car, they are shocked to discover that the victim was in constant contact with Voight's now-reformed son, Justin. After Lindsay and Voight find Justin has been attacked in the same manor and is critically injured, Antonio and the team know that Voight will be out for revenge. Meanwhile, Roman makes a difficult decision and Commander Crowley has plans to make changes within the unit.