While Tom McCarthy's parents are busy restoring Tregothyan Mill in Cornwall, he is trying to settle into life in the country, which is hard. Tom's bored already, wandering about with just the dog for company. At least when school starts he'll have something to do. Then Tom sees, or thinks he sees, a crone-like skeletal figure crouched under the old mill wheel, which sends the dog into a frenzy of barking. But when no one else can see it, Tom has a terrible feeling it is meant just for him. The figure then proceeds to haunt Tom, and his new friend, Holly. It is only when they are brave enough to confront it, that the 'spirit' tells them what it wants. It will not leave until it takes a soul with it, to avenge the original owner of the mill who wronged it. Tom and Holly have only one choice, to flood the spirit out of the mill, by tampering with the wheel itself - but time is running out for them . . .