Bekker takes drastic action to keep Rhodes from leaving Med for good. Meanwhile, Halstead questions Manning's feelings about their upcoming wedding, Ethan receives shocking news about his sister, and Dr. Charles mourns a loss.

The doctors and nurses of Chicago Med find themselves on high alert when an overflow of patients are rushed into the doors following a terrifying apartment complex blaze. Dr. Rhodes fights to save the life of one of Chicago Fire's own, while Dr. Halstead and his brother Jay struggle with their own personal battle.

The crossover starts on Chicago Fire S07E02 Going to War (I). It continues on Chicago P.D. S06E02 Endings (III).

When a sick boy is brought in, Ethan is faced with a tough decision that quickly escalates into a complicated and dangerous situation. Connor and Maggie are put to the test, while Natalie and Ethan aren't sure what to make of Elsa, the new third year medical student.

Dr. Halstead gets an unplanned visit from the CPD while Ethan is skeptical of a woman who is experiencing chronic pain. Natalie tends to a cancer patient whose brother has strong feelings on why he is refusing to lend his assistance

Dr. Manning and Dr. Halstead become skeptical of a patient's injuries when the victim of a car accident is brought into the hospital. Ethan and April have a difficult time understanding Emily's attachment to her boyfriend despite recent developments. Will and Natalie brace for their joint bachelor/bachelorette party.

The hospital is forced to evacuate when a toxic chemical is brought into the E.D., leaving patients and the staff in grave danger. Stuck in an elevator, Dr. Charles and Dr. Manning are forced to take drastic measures with a pregnant woman. Goodwin is tasked with making difficult choices and Dr. Rhodes discovers a secret that Dr. Bekker has been holding from him.

Dr. Charles struggles to convince Dr. Choi that surgery isn't always the answer. Dr. Rhodes finds himself in hot water with Goodwin when he disobeys her direct order. April becomes frustrated with Maggie when she continues to question her leadership role as the stand-in charge nurse. Dr. Manning suspects Dr. Halstead is keeping something from her.

Will and Natalie prepare for their big day, but an unsuspecting Will soon finds himself sidetracked. Dr. Charles disagrees with Goodwin on how to best handle a patient's treatment while Dr. Choi and April are on their own when a pregnant woman delivers. Dr. Rhodes finds himself operating on a patient that is of great importance to Det. Halstead.

April finds herself in a dangerous situation and Natalie gets an update on Will. Dr. Rhodes gears up for a gala honoring his hybrid O.R. and tries to convince Dr. Bekker to join him.

Halstead takes heat for making an unauthorized move to treat his pregnant patient. Choi becomes personally invested when treating a homeless veteran. Rhodes and Bekker deal with a patient who desperately needs a liver transplant.

Dr. Halstead rushes to rescue Dr. Manning after she is involved in a Medevac helicopter crash. The personal drama between Dr. Rhodes and Dr. Bekker boils over. Dr. Charles and Dr. Choi work to help a patient come to terms with their addiction. April helps Elsa deal with the loss of her first patient.

Halstead hides the theft of his gun from a suspicious Manning. Tensions are still high between Connor and Bekker, who take a risk operating on an HIV-positive patient. Hank breaks down when he sees a patient from his past.

The team deals with the aftermath of a school bus crash. Dr. Charles worries Dr. Halstead is putting his medical license in jeopardy. Maggie helps a friend in need.

The staff adjusts to the new normal of the pandemic. Dr. Choi, Dr. Lanik and April fight on the front lines. Dr. Halstead and Hannah face a troubling reality. Dr. Charles tries to clear the air with his daughter following recent developments.

Dr. Charles and April team up to take on a mysterious patient in the ED. Dr. Halstead is forced to make a life-or-death decision for one of his trial patients. Dr. Marcel is confronted by his past when a former acquaintance is brought into the ED.

Will runs into trouble when one of his trial patients falls ill. His own stress and symptoms have Ethan struggling to get through the day.

Ethan hires an old Navy colleague to join him in the ED. A final custody hearing threatens to separate Charles and his daughter. Maggie must make a choice that will change Auggie's life.

Crockett deals with a patient who ends up having more in common with him than he thinks. Will and Ethan clash over a pregnant patient with an irregular heartbeat.

Ethan teams up with an unexpected person to treat a famous tennis player who is afraid his career might be over. Goodwin's new protocols cause a stir.

Carol receives a second chance at life when a new heart becomes available. Ethan and Dean find themselves in hot water with an old patient. Will faces the consequences of the stolen trial medication.

Will Halstead returns to Med to help Goodwin with a secret investigation. Archer and Charles deal with twins who insist on being identical inside and out. Stevie and Dylan treat a young patient with sickle cell anemia.