Anthony Ferraris

Severide wants to implicate the serial arsonist, Dawson and Shay face the unexpected on a routine call, suspicions indicate Clarke is the mole, and Mouch campaigns for union president.

A rare but deadly bacteria takes its toll on numerous victims around the city, leaving Chicago's finest first responders to work together alongside the CDC to resolve the dangerous situation. Severide suspects something bigger is happening.

The mattress factory fire spirals out of control. Truck and squad lay it on the line in hopes of getting the trapped victims out alive.

Brett and Foster question the suspicious circumstances surrounding an attack at a juvenile detention centre. A convoluted new technology at Firehouse 51 tests everybody's patience and Kidd is chosen to represent the district at a leadership conference.

Severide and Stella keep an eye out for Grant; Louie has Dawson questioning her dangerous career path; Casey's relationship with Susan Weller cools down; tensions between Borrelli and Boden reach a boiling point.

Kelly is a law unto himself in his pursuit of Katie's kidnapper, while Dawson's grudge against Rebecca grows when she joins Firehouse 51.