When Martin's family moved house his Dad told him things would be better: he'd have more space to make his models, his sister would have her own bookshelves so she wouldn't use his ones and Dad would be doing all his beer brewing in the garden. Nobody said anything about a troll under the lawn! At first they think the troll is cute and funny but things never stay that way. Soon it takes over their whole lives and they realise they should have heeded the warning they found with it: DO NOT FEED THE TROLL!