In 1930s Los Angeles. Jack Parsons works as a janitor at a chemical factory by day, but, by night, he nurses a secret ambition: to build rockets that will take mankind to the moon. The pressures of his double life are further complicated when Jack and his wife Susan are confronted by a mysterious new neighbor, Ernest Donovan, who appears to be leading a double life of his own.

Feeling the pressure to succeed and provide Susan with the life he promised, Jack urges the rocketry team to take a risk and start testing their experiments at full volume. Sensing the Parsons' mounting frustrations, Ernest invites them to one of his group's secret gatherings, promising a way to make all their dreams come true.