After finding out that Casey intends to bounce Cordova from 51 due to issues with Herrmann, Gabby decides against telling him about her past relationship with Otis' sub. This, of course, backfires. Casey and the others are impressed when Cordova jumps in the pool after Kidd at a rescue scene, and that combined with the lackluster choices for another sub lead to Cordova's continued presence. Cordova joins the 51 team at Molly's, but runs into another old housemate who "outs" his past relationship with Gabby in front of Matt. Matt is upset with Gabby, who tries to explain why she didn't tell him. This only makes things worse -- Casey takes offense at the idea that he wouldn't be able to be impartial at work with one of her exes. Matt clears the air with Cordorva, but Gabby doesn't believe him when he says everything is fine between them. After Gabby gets caught between two gangs during an ambo call, she seeks Matt out to apologize again. He explains that he was hurt that she was leaving him out of her life again, and she promises not to put any more distance between them.
Kelly's mom shows up out of the blue, causing problems for Kelly and Stella. Not only does Stella try to hard to impress Jennifer, but Mama Severide is a church lady. When Stella tries to use the visit as an opportunity to clarify her relationship with Kelly, he dodges defining it, saying that it's between them and doesn't concern his mother. To Severide's surprise, Jennifer announces her intention to seek out Benny, saying that she wants to face him and make sure that he knows he didn't break her. But Kelly is even more shocked to return to his apartment and find his parents in bed together.
Otis is making good strides in PT, but Boden is obviously worried about keeping him around 51. He asks Otis to come back and help around the bullpen, which has been short staffed. Watching the team head out on a call without him is tough for Otis, but he does have a certain aptitude for administrative work: he has information ready before Connie needs it and clearly understands the office technology better than she does. He's also able to get through to a little boy rescued from a public pool that 81 brought back. Nobody had been able to get him to open up about his name or his parents or where he lives, and they're waiting for CPD and CPS to show up and solve the problem. Otis gets the boy's name, his dad's name, and his street out of the kindergartner, and the boy's dad comes to pick him up. Later, the mom shows up and accuses Boden and Otis of handing the child off to his "lunatic" noncustodial parent. Otis is beaten down by the mistake, and goes to the boy's house the next day to apologize to the family and try to convince them not to sue the department. While he's there, he figures out the whole thing is a ruse and gets photographic evidence that the family is still together. Bolstered by that success, he offers to come back to the bullpen...as a favor to Boden.