S3, E18: During a harrowing call to a structure fire, Herrmann (David Eigenberg) rescues a trapped toddler, but the questionable circumstances surrounding the event sends him on a personal mission to locate the father and get to the bottom of the situation. Severide (Taylor Kinney) makes up for lost time by retracing key friendships from his adolescence, while Mills (Charlie Barnett) discovers some surprising news. Elsewhere, Cruz (Joe Minoso) and Brett’s (Kara Killmer) relationship comes to a crucial juncture, while Otis (Yuri Sardarov) develops some unexpected feelings.