In the 70's, the Galaxy Quest sci-fi series' stars have ruled over space during four fertile years onboard the spaceship "NSEA Protector" in an extraordinary adventure quest running mission after mission with an unequivalent ardor. Twenty years later, the five heroes of the cult series still dress their uniforms and appear in some sci-fi conventions for the greatest joy of their fans who always request more autographs. But some of them come farther than they could guess from...
Confusing televised transmissions from the "Galaxy Quest" show, that they have intercepted, with historical documents, a group of extra-terrestrials comes to the convention and pushes "Commander Peter Quincy Taggart" and his crew in space in order that they help them to solve a space conflict, quiet real, that opposes them to a terrible adversary, the General Sarris.
Mathesar, the leader of the Theramin urges earthlings to come in their assistance against Sarris who wishes to negotiate in view of a surrender. First thinking they were facing a group of fans pushing the level of reality a bit far, the crew quickly understands that it is the truth and that the Theramin have built the "NSEA Protector 2" in all identical point to the one used for the series. But while they seek a mean to return back to Earth as quickly as possible, they are obliged to confront Sarris and win their salvation only thanks to their escape into an asteroid field.
Damages caused to the spaceship are important and deprive them from 87% of thepropulsion. It is necessary to find a Berylium sphere, energy used by the vessel. Fortunately, these spheres seems to be common on a little planet not far. Our new heroes board a shuttle and put course on the planet in the search of the essential fuel. Of course, things will be rendered more difficult when the group is going to meet a little alien race whose wickedness and hunger has no equal than their angel frail physics. With the assistance of the whole crew all will come back safe onboard the Protector, Taggart, escaping further more to a huge unpleasant rock monster.
But their escape is short duration. The vil Sarris boards the spaceship and Taggart sees in the obligation to confess the truth to Mathesar; they are not heroes but of actors of a tv series...
Spoiler ! the end of the story is revealed below…
Nevertheless, while they are on the way to be executed, a bravery and heroism vigor allows them to get rid of their assailants. After all they are interplanetary heroes, aren't they?. However, they not anticipated that Sarris and his men would release the self-destruction of the Protector. Not knowing how to stop it, Taggart, thanks to a transmitter accidentally exchanged during a convention, calls a group of fans among the fans who know the lesser nook of the spaciacraft and its technical possibilities. While Fred teleports the rock monster met on the Berylium spheres planet onboard the Sarris's spaceship, Taggart and Gwen desactivate the self-destruction mechanism of the Protector.
After a last explanation with Sarris's ship, the Protector separates into two parts allowing the Theramin to continue their way and the earthlings to realize an incredible landing in the middle of a "Galaxy Quest" fan convention making out of them forever famous heroes.