Casey and Severide disagree on a call 51 responds to where the firefighters find a car crashed in a frozen lake.
Severide wants to search the lake, but Casey says it's too dangerous.
Casey learns from police the accident looks like an attempted murder and believe the owner of the car, a woman named Lisa Burke, killed her fiance.
Lisa tells Casey her fiance drained her bank account and believes he staged the accident.
Casey and Lisa are eventually able to locate con artist and call the police.
Brett and Julie bond, but Brett is worried Julie won't have time for her once the baby comes.
Julie quells those fears when she reveals she is considering moving to Chicago, and Brett says she would like that.
Lily returns and wants Herrmann's help in starting a new business.
Herrmann wants to help Lily out with the rent, but he can't afford it.
Lily tells Herrmann she doesn't care about the money; she just wants his support and mentorship.
Boden is forced to diet by his wife Donna, and Kidd decides to join him in solidarity.
Gallo and Ritter prepare food for them, but Boden and Kidd eventually cave on the diet.