A mystic portal lies open. A chilling predator stalks the night. Can an undaunted student stop the darkness from spreading? Giles Chamberlain returns to a snowbound Cambridge after Christmas spent with his girlfriend. Determined to prove himself to her family, he sets out to discover what became of her missing brother. But when he encounters a sinister figure prowling the college's rooftops, he suspects last semester's creature was not the only entity to cross into our world. After the tight-lipped Professor Gupta refuses his plea for help, Giles enlists his feuding friends to locate the otherworldly passage. As hunters and hunted converge on the portal, the students discover just how far the old academic will go to keep his secret safe. Faced with forces beyond his imagination, can Giles conjure up the key to save them all?