Halstead's past resurfaces when a former Army colleague is implicated in a deadly blast. As the FBI launches an investigation into Roy's disappearance, Upton feels the pressure of the secret she and Voight are sharing.
When the body of a decapitated paramedic seemingly comes back to life, the agents begin to suspect the man may be an evolutionary freak capable of regeneration.
Jane discovers Red’s true identity. Ali, Tom and Pete face some family truths, unaware that Jane is in trouble. Jane convinces Bird to help her bring down Gomez permanently.
