In 1966, the Doctor defeated the Great Intelligence, but he knew it wasn't a final victory. And his companion Victoria, whose mind had once hosted the evil entity, might still fall prey to its power. Now it seems that his fears are justified. In a Tibetan monastery, the monks display unearthly powers — UNIT are investigating. A new university has opened in London with a secret agenda that may threaten the whole country. Victoria, abandoned in an age very different from her own, and haunted by visions of a father she refuses to believe is dead, is slipping into despair and madness. But are the visions which plague her really hallucinations? Or has the Great Intelligence once again made Earth its target for invasion?