The Sky Is Falling

S4, E13: The firehouse is on high alert when mysterious threats begin to emerge throughout Chicago. The situation turns dire when news of a mass shooting brings members of squad and truck into the middle of a dangerous and harrowing scene. Lt. Casey (Jesse Spencer) works diligently to investigate the missing money from the fundraiser for the victims of the recent tornado. Meanwhile, Jimmy (Steven R. McQueen) agrees to represent the firehouse in the first annual "Battle of the Badges" boxing match against the 21st district police department, and Chili's (Dora Madison) erratic behavior continues to be a major issue for her ambulance partner, Brett (Kara Killmer).