A sequel to Only You Can Save Mankind, these are the continuing adventures of Johnny Maxwell and his pals.
When saving mankind, Johnny was dealing with aliens and video games. Now he's developed a disturbing availability to see dead people. The cemetery he walks through on his way home from school is a pleasant enough place, but he wasn't expecting to be handed the job of preserving it from developers by the inhabitants. They're nice people, mostly - it's just that they're transparent.
Johnny rises to the occasion, of course, and Pratchett's warm-hearted tone really makes the story work.