The character Gemelas (Spanish for "Twins") manifests as identical female assassins employed by the Nazi occult organization Ahnenerbe. Deployed to Moscow to eliminate the protagonist Nadya, they move and act in flawless unison, exhibiting shared psychic abilities. Their primary narrative function involves relentlessly pursuing Nadya through the city, demonstrating supernatural tracking capabilities.

Clad in matching dark winter gear, their visual design underscores their role as cold, efficient killers. Their abilities enable silent coordination, often materializing suddenly during Nadya's movements. They serve as a persistent threat throughout the film's second act, embodying the occult force the Nazis deploy against Soviet psychic operatives.

Their narrative involvement concludes without explicit resolution as the focus shifts to the primary antagonist, Baron von Wolff, and the climactic confrontation with undead Teutonic Knights. The film remains the sole narrative source featuring these characters.