Casey and Dawson face the ultimate uphill battle in their efforts to keep Louie; Severide becomes emotionally invested in saving a stranger's life; a new piece of recreational equipment divides the firehouse.
Dawson and Casey learn that they have an opportunity to adopt Louie; Severide takes stock of his life and realizes he feels unfulfilled; Otis comes up with a once-in-a-lifetime idea to boost business at Molly's.
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.