On the Bring-Something-Old-to-School day, Milo's best friend Shane brings part of a carved ancient stone from his granny's wild garden.
When it is presented in class, Willie Jones's lizard goes crazy and leaps from its glass container in terror.
Milo realises this is no ordinary old stone. Afraid that his granny, Big Ella, will be annoyed with him for taking the carved stone, Shane asks Milo to mind the stone until the coast is clear.
However, Milo encounters a shadowy figure wearing a tall hat shuffling about in the garden.
This is the ghost of Mr Lewis, someone from the past and who is caught in a kind of limbo.
He too is searching for the piece of ancient stone, which is part of a druidstone.
He needs to find both pieces of the stone to lift a curse put upon him many years ago.
But where is the other half of the stone?