You are Phyllis Oakley, a dealer in rare books. You know all the tricks of the trade. You scour second-hand stalls, private auctions, secret bibliophile clubs, looking for what your clients seek. You have contacts all over London, lesser book-hunters and traders and barrow-rummagers who sometimes turn up something valuable. One of your most valuable contacts was Alf Fulbrow. Six months ago, you attended his funeral. Drowned, his daughter said. So who left that rare occult book on your doorstep last night? What ancient force, awoken from the slumber of three thousand years, stalks the streets of London?