Annika Boras

The detectives go undercover to arrest a man who brutally attacks other men; a deceptively tough defense attorney (Nia Vardalos) complicates ADA Barba's case.

The Machine issues the number of a prominent New York lawyer whose husband was recently murdered, and the team has to quickly determine whether she orchestrated the death, or if she is being framed. Meanwhile, Carter faces an issue with her new partner, Mike Laskey, after he spots her with Reese aka "The Man in the Suit."

The pursuit of a missing teenager leaves Mills and Brett stranded in unforgiving elements; members of the firehouse care for an abandoned newborn; Severide receives an intriguing proposal; Boden is at odds with his father (Richard Roundtree).

Evidence at a storage unit fire seems to be connected to the blaze that took Shay's life; Chaplain Orlovsky is in a car accident.

More clues emerge about the fire that killed Shay, leading Severide to a former nemesis; Shay's sister visits; Cruz is faced with a surprise; Boden tries to help his father.

Betty tries to make amends when Gio returns; Daniel receives some shocking family news.