Rhodes and Zanetti race to save a member of Firehouse 51; April's brother struggles during his first day at the hospital; a woman saved from a burning building leads to a bigger mystery.
Tommy Caffee's brother returns from being on the lam; Tommy's wife, Eileen, deals with her demons via drugs and alcohol.
Brody's efforts to sever ties with Abu Nazir triggers flashbacks to his time as a captive. Meanwhile, the mosque shooting results in a public-relations nightmare for Carrie.
Carrie needs to decide where her heart lies; Brody shares a drink with Faber; Saul embarks on a secret mission; Quinn makes a pivotal decision.
Emotions run high when Eric Matheson, accused of murdering his wife, takes the Lightman Group hostage to force them to help him uncover the real murderer.