Casey is unable to save a woman trapped in a burning house; Herrmann is determined to catch a mysterious tagger that targets the firehouse; Boden has an unexpected visitor; a teenager is injured during a romantic proposal.
Dawson is rattled by a suicide note she receives in the mail; Casey contemplates a life-changing purchase; Severide looks into Bloom's dark past.
The crew deal with an injury to one of their own; a temporary replacement needs to be dealt with; Kidd struggles to keep a secret; Boden considers some interesting news.
Boden pushes his team to pull it together in the aftermath of the explosion; Casey works to track down a missing Severide; Newhouse brings news about one of Mills' relatives; Herrmann and Otis come up with new goals.
A fire at a boarding school shakes Severide; Casey tries to help Dawson; Mills looks into his father's past.