Monster-Ace invades Challenger Mountain just as Red, Ace, and Prof zoom out in their new jet, the Gallopin' Gizmo. Monster-Ace runs wild and Challenger Mountain explodes! Villo summons the monster and the Challs follow. Rocky and Red are captured in trophy cases. Prof goes missing and Brainex stutters. Suddenly Ace morphs back to normal. Prof was inside Brainex rewiring him! Villo zaps the Challs outside with his vanishing beam, restores Brainex, and Villo's Villa soars away. And the Challengers need new headquarters!; Three Challs end up captives in cells with Villo holding the key. Rocky grabs the key, but when he unlocks his door, Ace becomes a giant monster. Villo splits via "vanishing beam" to his headquarters, Villo's Villa. His partner is the giant computer Brainex, and the two argue constantly. The monster wasn't in the plan (chemicals in the walls changed the explosion), but they can use him.; A mysterious cabal hires Villo, "The World's Vilest Villain," to kill the Challengers. Lured to Excito-Land, the Challs are attacked by the attractions.