The team races to save workers in a high-rise during a fire drill, car accident victims, and siblings fighting over a family heirloom. Buck gives Bobby surprising news. Eddie helps Christopher deal with the trauma caused by the tsunami.

Emergencies include a skating mishap at an ice show, an accident involving a self-driving car and a fulfillment warehouse robot going rogue. Meanwhile, Eddie's after-hours fight club gets out-of-control and Hen struggles in her relationship with Karen.

Hen fears for Karen's life when an explosion rocks her science lab on the day she brings Denny to work with her.

As Buck's life hangs in the balance, he dreams of a world where he never became a firefighter, for better and worse.