More clues surface surrounding the fire that killed Shay, leading Severide to a most unexpected source who may be able to provide pertinent information. Shay’s sister comes to town, prompting members of the firehouse to remember Shay’s life. Cruz is in for a surprise when Otis’ grandmother moves into their apartment. Boden finds a way to help his dying father make the most of his last few weeks. (A Little Devil Complex (2) aired on Chicago P.D., season 2, episode 13.)