Gus and Wally cannot help themselves when it comes to anything round and bouncy—which makes it awkward when Chimpsky entrusts them with the highly explosive BALL (Ballistic and Lethally Loaded).

Gus takes a game of Trash Torpedo too far, shooting Wally's beloved ukulele into space. To get it back, the Monkeys must face Pinky-Winky, a mean-girl space creature with musical plans of her own.

The citizens of GASI headquarters start disappearing by a bright blue flash and the monkeys plus YAY-OK must save them. The citizens of GASI headquarters had also turned into princess monsters created by an evil princess named Princess Monstare. Eventually YAY-OK tries to fight her, but she turns into a robot with him and the monkeys must save him and stop her.