In the midst of their visit, the neighbouring estate is purchased by the handsome young Marquess Ravensbrook. He seems a pleasant enough chap, though a strange medical condition making him extremely sensitive to sunlight apparently condemns him to a nocturnal existence.
Then Lady Anna's health begins to fail. She is plagued by strange, erotic dreams, with Lord Ravensbrook playing a leading role. On a nearby farm, a pretty young girl exhibits similar symptoms, then unexpectedly dies. A mysterious girl is found dead near the cemetery, her throat torn out, her body drained of blood. The local doctor is baffled. Called in consult, his old professor, Sir Ulrich Heilger, pronounces both Lady Anna's illness, and the deaths, the work of a vampire.
From that point, the race is on. Will the monster be found in time? Or will Lady Anna succumb?