Gabby and Matt head to the morgue, but the girl they were called about is not Bria. Gabby surmises that the dead girl stole Bria's bag, and, with a little help from Antonio, tracks Bria back to a youth shelter. After leaving word for the girl, Bria shows up at the firehouse. Gabby and Matt take her home, and petition to become temporary guardians. The caseworker is reluctant at first, telling them that her boss isn't going to want to give Bria special attention since she's caused trouble for the department by running off, but Matt steps up and convinces her. Later, when they take Bria to visit her dad in rehab, Matt explains to Gabby what really made him so uneasy about her interest in the teenager -- he was afraid she was pulling away from him like she did after they lost Louie. They reconcile and reaffirm their relationship. 

Cruz has an idea for a new firefighting tool to allow a single fireman to bust open a door, which is usually a two man job. The rest of the firehouse encourages his efforts, with Herrmann and Mouch seeing the profitability of such a tool. But it's Sylvie who lends him a practical hand, helping out with her heretofore unknown badass welding skills. When they finally get the Slamigan to work though, Otis notices something -- Cruz still has feelings for Brett. He calls his best friend on it, who insists that it's not a problem because he knows she doesn't feel the same way and he's not going to try to force anything. Otis is still concerned, and Cruz and Brett's so-called platonic date to The One Hundred fundraiser doesn't reassure him.

Kelly's old boss and mentor shows up, but it's not the reunion Severide is hoping for. Things go well at first, but Grizz expresses his disappointment in Kelly for not advancing further. Kelly gets upset and heads back to the apartment where he finds Stella and HazMat Zach continuing their date, which doesn't help matters. By the time of the fundraiser, he's over it, but Grizz brings up his career again, wanting to introduce him to "the right people" and ignoring Kelly's insistence that he's happy where he is. The final straw is when Grizz compares Kelly to Matt, who's made Captain. 

Stella is into HazMat Zach, but also hesitant about dating anybody after her run of bad luck. Things seem to be going well, but she bails on their second date at the last minute when Kelly asks her to go to the fundraiser with him.