Nurse Lockwood gets arrested when she takes a stand. Meanwhile, Dr. Halstead deals with a pending lawsuit against him; a baby's injuries come into question; Dr. Charles faces personal issues; and suspicions rise about a patient who was hit by a car.

An erratic patient arrives, claiming that his heart is pounding inside his head as he takes drastic measures to stop it. Also, Dr. Manning helps a boy with a broken wrist, but she suspects deeper issues exist; Dr. Rhodes impresses with his skills; and Will receives news about a lawsuit.

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).

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

When things become complicated, Will is forced to lie to Natalie. Ethan and April find out some compromising information about Emily's boyfriend and Ava is unsure of what to do with a patient who is refusing treatment.

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.

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 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.