Following the subway tunnel collapse, Ruzek and Kidd treat injured passengers and track down the missing offender.
After a daring rescue at an adventure park, Kidd asks Severide to create a ropes course for Girls on Fire. Violet's former nemesis returns, pleading for her help.
Chicago's first responders unite in the wake of a catastrophic gas explosion and fire that threaten a city government building. Herrmann reluctantly shadows Pascal while Violet, Novak and Dr. Frost take charge of triage efforts on site.
Cruz's past comes back to haunt him. Severide prepares to teach an arson class at the academy. Mouch searches for a victim's next of kin.
The team responds to a crisis at a community center. Severide is forced to investigate one of his own Squad members. Kidd helps a teacher going through a post-incident spin-out.
