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.

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.

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.

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 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.

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. Rhodes receives an alarming phone call that prompts him to rush out in the middle of an important surgery. Dr. Halstead comes to the aid of an FBI agent who is brought into the ER, but he suspects there is more to the story than he is being told. Dr. Manning and Dr. Choi find themselves on opposite sides of a major disagreement over doctor-patient confidentiality.

The hospital goes into lockdown mode when a man with a gun holds medical staff hostage. Goodwin is forced to make a tough decision. Dr. Rhodes begins to realize his time with his father is getting short.

Dr. Charles and Dr. Manning disagree on how to handle a patient who they discover is poisoning herself. Dr. Rhodes throws some serious accusations at Dr. Bekker. Dr. Halstead has suspicions about Natalie’s new boyfriend and Dr. Choi tends to Bernie.

Caroline has news to share, forcing Dr. Charles to make a serious decision about their relationship. Maggie meets her sister's new boyfriend, but discovers danger may lie ahead. Dr. Rhodes experiences a devastating loss while Dr. Choi and April are faced with an unexpected challenge that strengthens their relationship.

Dr. Charles and Caroline set some major plans. Ava fights to keep her relationship with Connor. Agent Lee informs Will of news that may put his life in danger.