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).

Dark family secrets emerge when Dr. Rhodes' father is honored for making a large donation to the hospital. Meanwhile, the Department of Homeland Security arrives when two injured airplane stowaways are brought to the hospital and Dr. Sarah Reese must deliver heartbreaking news to a boy.

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.