In spring 1944, Major Nemanja Lukic, a Yugoslav officer and British intelligence collaborator, arrives in war-torn Nis to investigate Major Heinrich Kahn, a Nazi occultist sent to unearth Constantine the Great's ancient weapons in the Serbian city's catacombs. Nemanja, with help from a gambler, a merchant, and a communist girl linked to British intelligence, learns Kahn seeks a mythical sword with supernatural powers derived from Christ’s cross.
Amidst this, Nemanja discovers the "Beast", a werewolf terrorizing the German soldiers and whose attacks are triggered by Kahn’s excavations. As Kahn prepares for mass murder to seize the sword, he faces opposition from Colonel Otto von Fehn and Captain Herman Richter, disillusioned by the Nazi’s brutal tactics. Nemanja is also ready to confront him, armed with his own secret vampiric powers.
