Will and Natalie battle for their lives after a car accident. An investigation is launched following the suspicious death of Cornelius Rhodes. Maggie receives life-changing news. Dr. Charles cuts his honeymoon short to tend to a patient.

A power outage at Med puts multiple patients at risk and tests the skills of the staff and their enthusiastic med students; Natalie returns following her traumatic brain injury; Ethan and April wonder if a family is in their future.

Dr. Manning's actions with a recent patient lead to serious repercussions. April and Noah disagree over a patient who is injured after a beating. Dr. Charles is visited by a childhood friend with a surprising revelation.

The crossover starts on Chicago Fire S08E04 Infection (I). It continues on Chicago PD S07E04 Infection, Part III (III).

Dr. Choi and Dr. Marcel don't see eye-to-eye over the treatment of a patient's chronic pain and rumors start to circulate about Maggie. Dr. Manning works to help a young boy, but her treatment suggestions are challenged by the parents who believe in only using holistic remedies.

Dr. Manning's actions with a recent patient lead to serious repercussions. April and Noah disagree over a patient who is injured after a beating. Dr. Charles is visited by a childhood friend with a surprising revelation.

Dr. Charles and Dr. Halstead sink their teeth into a bloodthirsty case. Dr. Marcel and Maggie throw a traditional crawfish boil for the staff. A new relationship blossoms while another is left on rocky ground.

Maggie gets unsettling news about a new friend and breaks protocol to support him. One of the doctors from the Med family is rushed into emergency surgery after a violent assault. A social media influencer lets his users vote on medical advice, forcing Dr. Charles to make a decision.

April receives unfortunate news that makes her question her future with Ethan. Dr. Charles and Maggie see tough times on the horizon. Natalie’s memory from the accident starts to return.

Dr. Halstead's world is thrown into turmoil when a former patient resurfaces. April has a secret she considers confessing to Ethan. Dr. Charles tries to maintain his focus during a difficult time.

After a major accident at O'Hare, the E.D. is concerned one of their own is in mortal danger. Will's proposal for a safe injection site goes to the board for consideration. Natalie and Goodwin become concerned for Gwen.

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.

Two brothers in critical condition are rushed into the hospital by their parents, leaving Dr. Choi, April and Dr. Charles to tend to their care and left to piece together what actually transpired. Dr. Manning becomes suspicious of a new mother entering the E.D. Dr. Halstead’s tireless activities at the safe injection site start to take a toll on his work.

Dr. Manning and Dr. Marcel disagree over an abusive husband. Dr. Halstead struggles with ethics and his decision to work at the safe injection site. Dr. Charles and Elsa reveal a misdiagnosis that may change a family’s life.

Dr. Charles and Dr. Manning treat a patient who is fully invested in pretending to be someone other than himself. Noah begins to doubt his abilities as a doctor. Dr. Marcel and Dr. Choi are faced with a tough ethical decision. Dr. Halstead puts his faith in an addict.

A convicted murderer’s escape hits close to home when several members of the team find themselves in danger. Dr. Charles and Dr. Halstead continue to clash over patient treatment plans. Dr. Choi and April discover the truth about a patient’s scam. Maggie finally receives some good news.

Dr. Manning and Dr. Charles assist in a complicated case helping a 4-year old who they quickly learn is no stranger to the ED. Dr. Marcel and Dr. Choi tend to a police officer with a mysterious gunshot wound to the abdomen. Relationships are put to the test as secrets are revealed.

Dr. Charles and Goodwin fear Dr. Halstead is repeating his past mistakes when a patient with early-onset Alzheimer’s is brought into the E.D. Maggie and Ben become concerned when one of Ben’s students is admitted. Dr. Manning and Dr. Marcel treat a terminally ill patient and disagree over the best course of action.

Dr. Charles evaluates a 15-year old who is brought into the E.D. after an apparent fall off an overpass. Will sides with Dr. Asher on a risky treatment plan. Tensions run high between Dr. Choi and Dr. Marcel.

Dr. Crockett is visited by two New Orleans detectives who have questions about his past. Dr. Choi puts his life in danger to save a child. Dr. Charles gives fatherly advice to his young daughter.