Betty tries to make amends when Gio returns; Daniel receives some shocking family news.
The team must figure out if a prominent lawyer orchestrated the murder of her husband or if she is being framed; Carter spots her new partner with Reese.
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.
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).
The detectives go under cover to arrest a man who brutally attacks other men; a deceptively tough defense attorney (Nia Vardalos) complicates ADA Barba's case.