The firehouse receives unsettling news when two of their own come up missing following a routine call, prompting members of Chicago P.D. to lead the search. Meanwhile, Casey and Dawson have a hard time figuring how to juggle their personal and professional lives. Elsewhere, Chief Boden and Donna struggle with news that their newborn has potential complications and they receive a surprise out-of-town visitor.

More clues surface surrounding the fire that killed Shay, leading Severide to a most unexpected source who may be able to provide pertinent information. Meanwhile, Shay's sister Megan comes to town, prompting members of the firehouse to remember Shay's life. Elsewhere, Cruz is in for a surprise when Otis's grandmother moves into their apartment, while Boden finds a way to help his dying father make the most of his last few weeks.