Synopsis

With the perpetrator of Chicago's bioterror attack identified, the Chicago Police Department gears up for its most extensive manhunt to date. Upton finds herself caught between the urgent need to assist in the capture of the suspect and the desire to offer comfort to a frightened young girl who desperately needs it. Voight harbors a growing apprehension that his team is being led on a fruitless pursuit. The crossover event begins with "Infection (I)" on Chicago Fire, Season 8, Episode 4, and