Tom and Twigs are learning to use a magic scroll that allows them to create objects by simply drawing them. Tasked with collecting slimeweed seeds by Treetog, they rush into drawing a machine to make the job easier. The Slimeweed Seed Express works a treat at first, but as they realise it's missing a brake, it runs amok. Now full of slimeweed seeds, the machine is snaffled by the Mushas, who attempt to drive it to the castle and create mayhem. It's a race to wrestle control back and save the castle from a slimeweed invasion.