With everyone’s support, Dawson makes final preparations to retake the fireman’s exam, but a call to the field may throw a major wrench into her plans. Elsewhere, Lt. Casey has an important matter to discuss with Antonio. Meanwhile, Lt. Severide and the firehouse welcome Rick Newhouse , the latest addition to the squad, Shay gets an uninvited surprise guest and Chief Boden makes a bold move.

A fire at a boarding school leaves Lt. Severide shaken and wondering if he could have done more. Meanwhile, with the firehouse in full support of Dawson as she retakes the fireman’s exam, Lt. Casey attempts some political maneuverings on her behalf. Elsewhere, Mills looks for answers about his father’s mysterious past and Chief Boden’s grand plans take a detour.

Boden forces members of Firehouse 51 to pull themselves back together in the aftermath of a harrowing fire explosion. While Severide goes missing for one week too many, Casey works to track down his whereabouts. Newhouse brings some unexpected news regarding one of Mills’ relatives. Herrmann and Otis make some new goals regarding Molly’s.

Severide returns to Firehouse 51, but he is clearly not his usual self. Dawson counts down the weeks until she gets started as a candidate at the Austin Firehouse. Mills learns more about his father’s family. Herrmann asks the rest of the Molly investors to come up with some new ideas to turn the business around.

Tensions run high when trucks from two firehouses collide and fingers are pointed towards Cruz for his driving.

A temporary chief fills in for Boden, who is forced to take some time off for personal reasons.

The interim chief makes a tactical error during an apartment fire, stirring up tensions and putting careers in jeopardy. Meanwhile, Mouch discovers that his donation to a fertility clinic has resulted in a child, and Dawson goes out on a double date with Brett and Cruz.