In 15th-century Transylvania, Vlad III, prince of Wallachia, strives to ensure peace in his kingdom, having abandoned his past as a fearsome warrior known as the Impaler. When Sultan Mehmed II demands a thousand boys, including Vlad's son, for his army, Vlad is desperate to protect his people and his family. Seeking the power to repel the Ottoman forces, he ventures to Broken Tooth Mountain, where an ancient vampire offers him supernatural abilities with a grim caveat: he will have extraordinary strength, speed, and command over the night, but will also develop an insatiable thirst for human blood.

The transformation is temporary, lasting for three days, after which Vlad will revert back to his human form if he can resist the compulsion to drink blood. Armed with his new powers, Vlad is an unstoppable force on the battlefield, decimating the Sultan's armies with ease. Despite his noble intentions, his subjects grow fearful of his darkening demeanor and the eerie occurrences that follow him. As Vlad struggles with the monstrous hunger growing within, he must also contend with the complex relationship with his wife, Mirena, who fears what her husband is becoming. His reign teeters on a knife's edge as he fights to save his kingdom from external threats and his soul from the eternal damnation of vampirism.