Ape Escape: On the Loose takes a trouble-making monkey on a wild ride. Chaos ensues when Specter gets hold of the Professor's Peak Point Helmet - Specter goes from a sweet, mischievous monkey to a power-hungry monster. After escaping from his cage he frees hundreds of monkeys from the zoo, and together they take control of the Professor's latest invention - a time machine, and escape into the past. Spike, a young friend of the Professor, pursues Specter and the monkeys and to prevent them from changing history and taking over the world.