S2, E22: A fire at a boarding school leaves Lt. Severide (Taylor Kinney) shaken and wondering if he could have done more. Meanwhile, with the firehouse in full support of Dawson (Monica Raymund) as she retakes the fireman's exam, Lt. Casey (Jesse Spencer) attempts some political maneuverings on her behalf. Elsewhere, Mills (Charlie Barnett) looks for answers about his father's mysterious past and Chief Boden's (Eamonn Walker) grand plans take a detour.