Katie finds an old piece of furniture in the basement and sets out to recreate her and Greg’s first apartment, reminiscent of a time when life was simpler. Meanwhile, Greg enjoys an unexpected benefit of being the victim of Lonnie’s relentless practical jokes.
Severide teams up with Seager and the OFI when a motel structure fire turns suspicious. Firehouse 51 members become amateur sleuths following a Reddit post involving one of their own. Brett continues to get invested in her birth mother.
Moody is envious of Pearl's friendship with Lexie, as Lexie enjoys her newly sexually-active status with Brian. Inspired by Lexie, Pearl explores her budding sexuality and sets her sights on Trip. Mia and Elena find themselves at odds over Mirabelle/May Ling, which ends in an epic showdown and launches a custody battle.