The members of Firehouse 51 struggle to cope when one of their own dies in a fire, while lieutenants Casey and Severide blame each other for the tragedy.
Gibbs and the team must take action after the director's risky solo meeting with an informant results in a death.
Severide hides his serious shoulder injury as he tries to rescue a construction worker from a collapsed building; two teens become trapped in a vehicle.
Casey must decide whether or not to turn in a dirty cop's son who paralysed a teen in a drunken-driving accident; new girl Nicki pays Severide special attention.
Deeks is forced to assume an old alias, in order to protect his best friend and chief informant from arms traffickers. Things begin to get personal.