Heather is such a whiny little brat. Always getting Michael and me into trouble. But since our mother married her father, we're stuck with her ... our "poor stepsister" who lost her real mother in a mysterious fire. But now something terrible has happened. Heather has found a new friend, out in the graveyard behind our home—a girl named Helen who died with her family in a mysterious fire over a hundred years ago. Now her ghost returns to lure children into the pond ... to drown! I don't want to believe in ghosts, but I've followed Heather into the graveyard and watch her talk to Helen. And I'm terrified. Not for myself, but for Heather...

    

    The ghost is a poltergeist that William calls 'Poldy'. At the beginning William and Poldy play a friendly game every night, but then the game begins to change. It becomes a dangerous game. Who will win?