Heartstone

Jeremy isn't surprised his grandfather died. He's surprised he had one.

When the family travel to Cumbria for the funeral arrangements, he realises his grandfather had an important job to complete. Jeremy's grandfather was part of the Order of the Magi, who trapped an evil spirit away from our world, using the power contained within heartstones, and hidden in special places around the county.

But the heartstones need recharging every hundred years, so Jeremy and his strange new friend must find each stone, and complete dangerous tasks to prove they are worthy, before the power of the stones runs out and evil has control over the world.