Johnny and the Dead — Terry Pratchett

Sell the cemetery?
Over their dead bodies.

Not many people can see the dead (not many would want to). Twelve-year-old Johnny Maxwell can. And he's got bad news for them: the council want to sell the cemetery as a building site. But the dead have learned a thing or two from Johnny. They're not going to take it lying down... especially since it's Halloween tomorrow.

Besides, they're beginning to find that life is a lot more fun than it was when they were...well... alive. Particularly if they break a few rules...