The team is on high alert when a previous incident during a fire call leaves a dangerous man on the loose with a vendetta to target Lt. Casey and Firehouse 51, and prompts CPD to step in. Dennis Mack, a buddy firefighter of Severide's father, comes to town to shadow the squad but may have ulterior motives. Meanwhile, Brett and Antonio's relationship hits some bumps in the road when his ex-wife Laura surfaces and Casey has a present for Dawson.
Elenco: Jesse Spencer , Taylor Kinney , David Eigenberg , Joe Minoso , Christian Stolte , Eamonn Walker , Yuriy Sardarov , Kara Killmer , Monica Raymund , Miranda Rae Mayo , Charlie Barnett , Lauren German , Annie Ilonzeh , Alberto Rosende , Dora Madison , Steven R. McQueen , Daniel Kyri , Hanako Greensmith .