Banned from using the Anti-Proton Gun by the United Nations, Capt. Perot sets out to destroy a moon of Jupiter to prove the effect. Astro follows to stop him and engages in battle with Atlas, who has come to steal the gun because Jiss, who is alive, takes Livian hostage. The moon is destroyed by the gun. Livian escapes after telling Atlas that Astro is his brother. Jiss is eliminated.