The Black Dragon is set in 436 AD. The Roman Empire is dying. The world is in chaos and no one knows why, Decurion Flavius, fleeing the wrath of the Roman Imperial Army, is on his way to the Rhine, the land of the Burgundians to join King Gunther's War Horses. Though he doesn't understand why, Flavius had killed his friend, Otho, and stolen his unit's payroll. While on his journey, Flavius is ambushed by an evil dwarf named Fire Cheek. His people, who call themselves Lanbrotxirip or Mist Folk. They once molded and ruled the world, until the arrival of the “tall folk” who honored not the old ways, but gradually pushed the Mist Folk into the forest. Without being told, Fire Cheek knows who Flavius is and where he's going. He even knows that the Decurion's German name is Siegfred Siegmundson.

Simply put, Fire Cheek wants Flavius to kill Gunther. He gifts him with a large bundle of valuable coins and a vial of poison. The Decurion tries unsuccessfully to get rid of both. He has no intentions of killing Gunther. He doesn't even understand why he killed Otho. But enchantment is stronger than his good intentions. Flavius, who is half German, has no trouble being accepted as one of the Biscuit Eaters, as Gunther's men are known.

While at Gunther's court, Flavius has several opportunities to slip the poison into the king's cup. But he resists. He also meets Domina Gutrune, the king's sister. At first the lady seems to dislike him, but then that changes. She tells him point blank that she wants him to deflower her. It seems that Gunter is planning to marry her off to Atila the Hun. This action, she believes, will spoil the plan. But in this land of enchantment can he trust her? Can he trust anyone?