Young Peter, a student of Byzantine Art at Moscow University, receives through a cryptic sentence in a lecture, a message to buy two books of his choice at a specific hour in the University bookshop. When he opens the package, a third book has been included. It is the third book which sends Peter on a series of adventures leading to the unravelling of a mysterious power source guiding the destinies of planet Earth. His quest is allso intimately linked with his father's baffling disappearance. Once again the Hoyles have succeeded in combining an enjoyable piece of story - telling with specific speculation of lasting interest.