The MI High agents are protecting Dr Wallis, the inventor of The Mind Machine, a device that turns bad people good. However, the evil Grand Master has got wind of the device and wants to use it to turn good people bad, and sends a SKUL agent to capture Dr Wallis and his invention.

Jed Black, MI9's head of training, arrives at St Hope's to get the spies fit and they endure a day of exercise. Meanwhile, a strange newcomer, Luvabitz, arrives in his wurst van and hands out the free, greasy, delicious wursts. The kids and Frank become addicted and simply cannot get enough of them. As a result, they are getting fatter and fatter. Where will it all end?