A dangerous warehouse fire puts truck and squad at risk. Tensions rise for Dawson and Casey as Dawson's father overstays his welcome at their home. Mouch considers retirement.
Severide watches over Detective Holloway's son while she testifies in court as part of an undercover operation, but he's left to deal with the situation due to an unexpected turn of events.
Members of Firehouse 51 transport victims of a gas leak to nearby Chicago Med; an armed patient claiming to be carrying a deadly airborne disease forces Chicago Med into lockdown.