A world of illicit drugs and addiction is uncovered while investigating a brutal stabbing in a bad Las Vegas neighborhood.
An escalating gang war spills into the stands of a high-school football game, killing several people; an unlikely partnership arises.
Dawson and Casey's relationship is tested as the team responds to a truck leaking hydrochloric acid in a busy intersection; Severide learns about Brittany's past; Mouch has dating troubles.
Two firehouse members are abducted, triggering a desperate search by the Chicago P.D.
A house fire puts a couple in danger; Dawson and Casey are pushed apart; the Chicago Holiday Fest gives Molly's II a chance to shine.
