A pest control problem forces the 51 team to temporarily bunk with Firehouse 20. Casey clashes with Delaney. Foster, Kidd and Brett fear Leone has it out for them. Boden mulls a procedural overhaul.
Phil pays a visit to his dad after hearing some concerning news about him; Jay gives Claire and Mitch a bunch of their old childhood memorabilia that triggers them to reevaluate a long-held story about their first family vacation.