England, 1888. A monster stalks the foggy streets of London. A loathsome, villainous beast wantonly killing all who get in his way – be they man, woman … or child. When his dear sister is brutally slain, the young man known as Greenwich vows vengeance – but he cannot bring the killer to justice alone. With the help of Arthur Conan Doyle – a man whose deductive ingenuity matches that of his fictional detective Sherlock Holmes – Greenwich must reveal the murderer’s dark purpose and uncover the shocking truth. For this killer is not a man at all. This killer is made from the very mud of the River Thames itself … And what hope does a mere man have against such magic?