In the year 1900 Eric and Gunter von Schwartzwolf are little boys growing up in their family’s half-ruined castle on the Baltic coast of Livonia. In the old cemetery behind the castle they discover an underground vault and a secret cave that contains a mysterious relic: The Old Iron Box. Their Mongolian nursemaid tells them that “There is nothing down there but old bones.”

On the next full moon the boys watch while The Old Iron Box is carted away by equally mysterious Orientals, but their father, Baron Theodore von Schwartzwolf tells them: “I have The Book and I have The Key…And when you are full-grown, one of you shall have them both,” Their mother watches from the castle window. She knows which of her sons was born with the Mark of the Beast and she prays for his soul.

In 1904 the Russo-Japanese War calls Colonel Theodore von Schwartzwolf and his family back to Siberia where he commands a Mongol Cossack regiment. The boys grow into teenagers as Mongols, under the tutelage of Lama Chono Dorje who is an elder in the ancient Wolf Cult. While they are stationed in Siberia the boys befriend Elena Igorovna, the teenage daughter of Grand Duke Igor Romanov, their father’s commanding general.

Germany declares war on Russia in 1914. Gunter, with his father’s influence, has obtained an officer’s commission in the Tsar’s cavalry, while the more scholarly Eric is off to the university at St. Petersburg.

On their last night in the castle old Baron Theodore interrupts a fight between the two brothers over the old book the Canii Deus which Eric is trying to translate from Latin to Russian. The Baron has decided to give The Book and The Key to Gunter even though his is not convinced that Gunter has “The Legacy” in his blood. When Gunter asks “Where do I find “The Old Iron Box?” Baron Theodore replies: “Distinguish yourself in battle and perhaps it will find you.”

Gunter von Schwartzwolf goes off to war while his brother Eric falls in love with the now grown-up and beautiful Grand Duchess Elena Romanov. Gunter returns and seduces Elena, but a horrifying black wolf nearly kills them both. Eric is disillusioned and bitter. He joins the Bolsheviks.  Elena, as a lady in waiting upon the Empress, is entrusted to conceal the most valuable of the Russian Crown Jewels, the Polar Star Ruby. In the chaos of the Revolution she and her family are separated. Gunter quickly becomes a leader in the White Russian resistance movement. Elena’s father Duke Igor gives him command of a Siberian Cossack division to invade Mongolia, where he hopes to find The Old Iron Box -- then he will raise a Mongol horde to re-conquer Russia.

But before Gunter can launch his invasion he is wounded and disfigured.
Meanwhile Eric becomes a commissar aboard a monstrous armored “Death Train” sent out to loot the Russian churches and recapture the lost Romanov gold. The atrocities the Death Train’s shock troops are inflicting on the defenseless priests and nuns disturbs Eric. A black wolf takes revenge on the Cheka troops. -- and then Elena Romanov reappears as a helpless refugee whom he now protects.

With eyes glowing feral yellow Eric destroys the Death Train and escapes with Elena into the wilderness of Siberia. They winter in the cabin of Ivan the cannibal while Eric bonds with the wolves and forges his wolf-claws. In the spring they journey to Mongolia where Gunter has become a feared and hated mystic warlord known as “The Mad Baron.” Here the two brothers will confront each other in a climactic duel to decide which one will inherit the family’s dark legacy, and uncover the final secret of The Old Iron Box.