When the decapitated body of a woman found in Lake Michigan is connected to Voight's (Jason Beghe) social circle, Lindsay (Sophia Bush) fears his relationship with the group may hinder his ability to approach the case objectively. Roman (Brian Geraghty) is having a hard time coping with recent events and an error in judgment causes him to make a grave mistake. Meanwhile, Olinsky (Elias Koteas) becomes upset when Antonio (Jon Seda) doesn't consultant him before making a decision that could affect Michelle's (guest star Madison McLaughlin) future.
A doctor with personal connections to Voight (Jason Beghe) is under investigation when four of his patients are committed to Chicago Med after an overdose of chemo. The doctor denies Lindsey (Sophia Bush) and Halstead (Jesse Lee Sofer) access to his files, but after obtaining a warrant the team is able to track down his patients and discover all of them have been poisoned with unnecessary chemo. Meanwhile, Burgess (Marina Squerciati) and Platt (Amy Morton) work together to clear Roman's (Brian Geraghty) name.