S4, E2: Members of the firehouse are frustrated with their inability to help Chief Boden (Eamonn Walker), whose job is on the line pending an internal investigation in the aftermath of a complicated call to a fire. Meanwhile, Lt. Severide (Taylor Kinney) struggles to accept his smaller role and adjusts to the presence of Capt. Patterson (guest star Brian White), his new commanding officer. Dawson (Monica Raymund) shakes things up on the work front and Casey (Jesse Spencer) attempts to find a crucial piece of evidence in his ongoing investigation against Nesbitt (guest star Eric Mabius). Elsewhere, Herrmann (David Eigenberg) struggles to keep the peace with Molly's newest neighbors.