A ship has crashed on Amzot, and Zandor and Zak check on the alien. He says that he is okay and that his people are on the way to help repair his ship. Zandor and Zak leave and the alien reveals himself to be a Mutoid. The Mutoid contacts his leader, Mutak, and tells him that all is going according to plan. Mutak tells him that they are on their way and will be there shortly.
Dorno, Gleep, and Tundro are enjoying playing in the water of a pond when they see three ships fly over and they go to investigate. They find out that the three ships are not there to repair the other one and Dorno wants to go tell Zandor. The Mutoids spot them and attack. Gleep goes to get Zandor and the Herculoids to rescue Tundro and Dorno.
Gleep makes it to Zandor and tells him what has happened. Zandor tells the Herculoids to move out and they find Dorno and Tundro under attack from the Mutoids. Zandor, Zak, and Igoo defeat the Mutoids and demand that Mutak surrender. He agrees to do so but sets a trap for them.
Zandor and the Herculoids arrive at the Mutoids' landing site and Mutak tells Zandor that he is going to use Amzot as a launching site for his missiles to fool his enemies. Zandor tells him that he will not allow this and then Mutak springs his trap. The Mutoids had desguised themselves as rock formations and they now appear and begin to attack and Mutaks launches his missiles.
Zandor, Dorno, and Gleep head for Mutak's ship in order to stop the missiles while the others take care of the Mutoids that are attacking. Zandor and Dorno make it to the control room and Gleep knocks Mutak out of the room. Zandor tells Dorno to destroy the missile launching controls while Zandor destroys the missiles. Mutak disguises himself as Zandor and tells Dorno that he will destroy the controls.
Everyone makes it outside and they discover that Mutak tricked Dorno and he is now trying to get away and launch his missiles. Dorno tells Zak to stop him and Zak melts a hole in a flat boulder, then takes the boulder and drops it on the top of Mutak's ship. Mutaks tries to launch the missiles and they explode inside his ship because the nose cone won't open. Zandor and the Herculoids hope they never see the Mutoids again.