Chicago Fire (2012)

S5E12 An Agent of the Machine

The team is on edge as a past fire call incident has unleashed a vengeful man who is now targeting Lt. Casey and Firehouse 51, prompting the Chicago Police Department to get involved. Dennis Mack, a friend of Severide's father, arrives to observe the squad, but his true intentions raise suspicions. Meanwhile, Brett and Antonio encounter challenges in their relationship when his ex-wife, Laura, makes an unexpected return. Additionally, Casey surprises Dawson with a thoughtful gift.