context: For the plot of the film-within-the-film, see This Island Earth
  The film opens with mad scientist Dr. Clayton Forrester, working from an underground laboratory, explaining the premise of the film (and associated TV series). Mike Nelson and the robots Crow T. Robot and Tom Servo, along with Gypsy, are aboard the Satellite of Love high in Earth's orbit, when Forrester forces them to watch the film This Island Earth to break their wills; as per the television show, Mike, Crow, and Tom riff the film as it airs.
  The film-riffing scenes are book-ended and interspersed with short sketches. Prior to the film, Crow attempts to dig through the ship's hull to return to Earth. After the filmstrip breaks and Forrester reloads it, Crow and Tom dare Mike to drive the Satellite himself, but ends up crashing into the Hubble Space Telescope; Mike then tries to repair the Hubble using the Satellite's manipulator arms, MANOS, but instead further damages the unit before Gypsy takes over. Some time into the film, Tom reveals that he has an interocitor like that used in This Island Earth. The gang tries to use Tom's device to return to Earth, but instead contact a Metalunan (the alien race from the film) who is unable to help them to figure out how to use it correctly but does accidentally repeatedly zap Tom's head with a laser beam. The contact is broken by Forrester, who also has an interocitor, and he zaps the group to encourage them back to the theater.
  After the film, Mike, Crow, and Tom are far from broken, celebrating in various Metaluna ways. Forrester, furious at his failure, attempts to use his own interocitor to harm Mike and the others, but only succeeds in transporting himself into the shower of the Metalunan previously seen. Mike and the robots briefly celebrate Forrester's disappearance before they realize they no longer have a way back to Earth without him. Upon this realization, the crew goes back to the theater to riff on the film's ending credits.
question: the  scientist explaints what type of story?
answer: premise of the film