Mrs Peterson gives her class a big new project - they have to find something they can sell at Tunbridge Town Fete. At first, Justin`s group don`t know what to sell, but then Justin has a bright idea - they`ll sell `worm juice`. Worm juice is a wonderful fertiliser for plants! But Justin and his friends soon discover that setting up a worm farm isn`t easy, and as the date of the fete gets closer, they wonder if they`re going to have anything to sell!