Betrayed by the traitor Wyvern, the search party of Jessica Sumerisle, Saul Petrus, and the mysterious Seeker Jane was attacked on an abandoned London Underground platform and had their blood-won prize abducted by demons. The desperate team now must venture into the rotten heart of London, infested by gruesome hellbeasts, to reclaim their last hope for survival. This ancient tome, the Harbour of Knowledge, may be the key to driving all of Hell's loathsome creatures back from the face of the Earth . . . but have they judged a book by its cover?