Frustrated and disillusioned physicist Dave Crowell has found a temporary and undemanding job - 'piloting' a flying saucer mock-up spaceflight simulator at a third-rate amusement park - to escape from his former Defense Department employers' demands to develop more effective weapons of mass destruction.
However, an alien from the planet Empyria stealthily modifies the attraction into an actual interplanetary spacecraft; and, passing himself off as a weird roving sideshow, invites aboard a group of misfits, each of whom is refusing to confront unpleasant realities in his/her life.
The Empyrian offers the group a second chance to better themselves - an opportunity to colonize a small planetoid called Tythra that, paradoxically, will threaten both the alien's home world and Earth, just 82 years down the line; by inhabiting it, the colonists will alter its orbital path and thus avert the disaster.
Instead, he advises him to seek help directly from Earth's governments and scientists, in order to initialize a proper collaboration for the sake of each individual, by asking for volunteers to accompany them to Tythra - he assures the alien that he would probably have a whole ship full of people willing to receive a second chance at life.
The script was rewritten as "Second Chance" by Lou Morheim, who retained the basic plot but threw out most of the emotional depth and humor of the characters, supposedly because ABC wanted monsters and simplistic stories.