At the height of the depression in Gladstone, Queensland, there have been repeated hold ups in shipping grain from the harbour. As a result, all of the storage sheds have been full of bagged grain for much longer than normal and a rat plague begins.
The Harbour Board offers a reward of ten shillings per foot for live pythons that are placed in the sheds to eat the rats. Snake Eyes and his gang of primary schoolers go into business snake catching.
As the rat plague spreads to the small coastal town, the Council declares a bounty on rats of sixpence a head. Rats are numerous and Ratface and his gang set up shop as catchers in the rat trade.
Conflict arises between the gangs, but between their hostile billy-cart races and flour-bomb fights, they uncover an opal smuggling operation using both rats and snakes, and involving some important townspeople. Consequently, they work together to reveal the culprits to the adult world.