Will and Natalie prepare for their big day, but an unsuspecting Will soon finds himself sidetracked. Dr. Charles disagrees with Goodwin on how to best handle a patient's treatment while Dr. Choi and April are on their own when a pregnant woman delivers. Dr. Rhodes finds himself operating on a patient that is of great importance to Det. Halstead.

Natalie and Maggie witness a pickup truck plow through a street fair and must make tough decisions on the fly. At the hospital, doctors and nurses are on high alert with the influx of patients. Dr. Charles' ex-wife comes to town with news.

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.

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. Marcel and Dr. Manning lay everything on the line to assist a sick woman. Dr. Halstead faces an uphill battle in getting participants involved in his clinical trial. Dr. Choi clashes with a patient who demands absolute perfection of himself.

Crockett deals with a patient who ends up having more in common with him than he thinks. Will and Ethan clash over a pregnant patient with an irregular heartbeat.