Jimmy Zest is an inventor and, he likes to think, the brains of his class. The trouble is, nobody knows what crazy idea will come to him next and which of his friends - Gowso, Mandy, Penny Brown, Knuckles, Shorty or Legweak - will be persuaded to join in the mayhem. Six funny stories in which Jimmy - sometimes with the help but more often the hindrance of his mates - puzzles Penny Brown, designs a dinosaur with a difference, starts a Strong Stomach contest, sets up a spectacular cycling stunt, mollifies a monster and makes a money-box like no other.