Jack Slater is an official Monster Investigator - licensed to hunt out monsters who turn up under beds and terrorize small children (and his parents!). Armed with a high-power torch (monsters hate the light), a pocketful of spare batteries and a much-loved teddy (there is nothing monsters hate more than a favourite childhood toy), he sets off down to Monster Underworld when news reaches his ears that the monsters are on the march. They're getting organized and no-one, not even the Prime Minister in Downing Street, is safe any more...