Amber Appleton (Auli'i Cravalho) remains an optimist even when her personal life is far less stable than it appears on the surface. A musically gifted high school student with aspirations to attend Carnegie Mellon, Amber balances her beloved high school drama club helmed by Mr. Franks (Fred Armisen) with working long hours at a donut shop to help support herself and her down-on-her-luck single mom (Justina Machado). She also spends time at the local retirement community, giving care and...

A waste disposal company has a Russian nuclear bomb to transport, and an employee decides to save money by concealing it on a freight train. The train, also loaded with hazardous and flammable chemicals, suffers a brake failure and becomes a runaway heading for Denver. A wreck would be bad enough, but much, much worse if the bomb goes off. A heroic NTSB investigator boards the train; he and the railwaymen try various ways to stop the train, but nothing works. Meanwhile Denver residents are...