Space Ace and the Space Mutts are assignede to gaurd a precious item at the museum. The Zodiac Man appears and steals the item and challenges Space Ace to try and catch him. He disappears and Space Ace and the Space Mutts run outside to get in their ship to follow him.
Zodiac Man leads Space Ace and crew through an amusement park and uses a gaint metal goat to try and stop them. Astro accidentally puts the ship in reverse and they fly right into the beast. They bounce around a few time and the metal giant explodes.
Space Ace and crew track down the Zodiac Man to his hideout and after a brief fight, Space Ace turns the tables on Zodiac Man and they haul him off to prison as their ship is being towed.