The grand opening of Chicago Med's emergency department is interrupted by victims of an elevated train crash, pushing the staff to their limits.

Dr. Choi treats a teen mother who abandoned her newborn baby in an alley, as the staffers must make difficult decisions about the teen's future. Also, a hypochondriac with chest pains is treated, as is a patient suffering from possible dementia.

Dr. Rhodes must confront his past when he treats a close family friend who's been impaled by glass in a case that reunites him with his sister. Meanwhile, a musician must decide to undergo surgery that will save her life but could destroy her hearing.

The doctors treat victims of a movie-theater shooting as Sharon Goodwin tries to keep the press at bay. A teen with an eating disorder is treated, but Dr. Charles' methods rub others the wrong way. The staffers deal with a racist patient.

A member of Firehouse 51 clings to life and takes a sudden turn for the worse as medical staffers race to give treatment. Meanwhile, Dr. Natalie Manning prepares for her pregnancy and members of Chicago P.D. probe the case of a woman pulled from a fire.

The crossover starts on Chicago Fire S04E10 The Beating Heart (I). It continues on Chicago P.D. S03E10 Now I'm God (III).

Sharon Goodwin puts her job on the line for a patient in need of a lifesaving bone-marrow transplant. Meanwhile, April cares for a homeless man, Dr. Manning's parents arrive, and a couple are injured during their first date by a hit-and-run driver.

Dr. Manning returns from maternity leave and treats a teen with a history of medical issues. Meanwhile, Dr. Choi cares for a former Navy shipmate; a Saudi prince arrives for a surgical procedure, but only from a hotshot surgeon; and a romance blooms between Sarah and a lab tech.

Dr. Halstead jeopardizes his career when he goes against a family's order regarding a terminally ill cancer patient. Meanwhile, April and Dr. Reese treat a homeless man, and Choi's personal issues emerge while caring for a bipolar patient.

A 9/11 hero is treated, but an unforeseen medical problem arises. Meanwhile, Sarah contemplates which hospital to select for her residency; Dr. Choi cares for an injured teen hockey player with a demanding father; and Halstead and Manning clash.

Dr. Rhodes and Dr. Choi clash over the final decision made by a dying patient. Meanwhile, a pending lawsuit against Dr. Halstead moves forward, and doctors race to save a patient with a misdiagnosed flesh-eating bacterial disease.

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.

A husband makes a request following his wife's death; Dr. Charles tries to reason with a patient who wants to remove his own arm from his body; a child arrives at the hospital after swallowing magnets; Sarah has last-minute thoughts about her residency.

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.

A teen patient with abdominal pain firmly refuses any drugs. Meanwhile, Dr. Halstead reconnects with his past when treating a patient; a pregnant woman does everything in her power not to deliver the child; and Dr. Rhodes tries to avoid family issues.

Dr. Rhodes and Dr. Downey clash over how to treat a patient with various health and heart issues. Meanwhile, excessive hoarding at a home comes into play when trying to help a man with a leg injury; a patient is bitten by her own dog; and a commission pays a surprise visit to evaluate the hospital.

April and Dr. Halstead clash over how to treat an alcoholic homeless man with a broken leg. Also, Dr. Manning continues to grieve over her husband's death; two elderly women with the same symptoms share a surprise link; Halstead mulls over a job offer in California.

Dr. Rhodes treats his mentor and Goodman faces personal issues in the Season 1 finale. Also: April deals with a disorderly patient; Dr. Manning's past catches up with her; and Sarah's graduation day arrives, but she remains conflicted about her future.