Decades after the success of the sci-fi series "Galaxy Quest," the show's washed-up stars -- Jason Nesmith (Tim Allen), Gwen DeMarco (Sigourney Weaver) and Alexander Dane (Alan Rickman) -- are recruited by actual aliens to pull off an intergalactic rescue mission. At first, the actors assume the so-called Thermians are just another group of die-hard fans. But as the plot thickens, they realize they're working with real-life extraterrestrials.