Antonio brings Brett to a much-awaited Dawson family gathering; the firehouse becomes concerned over the well-being of Boden's stepson, James; Herrmann volunteers Otis and Kidd for a charity competition event.
Casey and Severide continue to clash over a potential arson case; meanwhile, Dawson has a startling incident that gets her in hot water, and the mysteries of Boden's past intrigue the firehouse. Brian Baumgartner guest stars.
After responding to a deadly fire, Casey and Severide come to blows over the circumstances behind the incident; Herrmann and others launch a campaign to identify a persistent tagger who's been vandalizing the firehouse.
Facing political pressure from another alderman, Casey will stop at nothing to keep his family intact; meanwhile, spurred on by a social media celebrity, Severide considers taking a break from Firehouse 51 to pursue a different lifestyle.
Severide disagrees with Kidd's methods in handling her dangerous ex; Borrelli becomes a liability for the firehouse, forcing Boden to make difficult leadership decisions; and Casey and Dawson must fight to maintain their family.