A Gothic vampire tale of intrigue, fantasy, horror, mystery and seduction, set against the backdrop of the Victorian London smog and the murky shadows of the Austro-Hungarian empire.
 
Lieutenant Albert Montague has been confined to his London home with a crushing illness since the Crimean War. Haunted in his sleeping hours by a mysterious woman, and in the daytime by a ghostly man, he sails to Hungary on a tall ship. Meanwhile, in Budapest, Professor Franz Polanyi discovers an old Turkish chronicle. Confirming his worst nightmare, the document refers to a dreadful and remote citadel of evil. Determined to discover its source, he becomes drawn into a darkening crisis involving the desecration of a grave and a number of unexplained abductions. In the midst of these shadowy events, Montague falls prey to the allure of a beautiful and dark aristocratic lady, and lives in dread of his phantom assailant; but is seemingly rescued by the stabilising influence of Major Carl von Metzger. After a chance meeting, von Metzger, Montague, and Polanyi unite against the ever-increasing threat of a terrible enemy, and a race against time in Budapest, the remote Hungarian countryside, Vienna and Pressburg. Will Montague succumb to the mysterious seductress? Can the fortress of terror be found and its deadly secrets unlocked? Or will the powers of darkness prevail?