Sir Borotyn, a prominent Prague resident, is discovered murdered in his home, with all indications pointing to a vampire assault. The victim's friend, Baron Otto, and the physician who analyzes the body are certain that the vampire is the mysterious Count Mora, or perhaps his daughter, but receive little help from the law. Professor Zelen, an expert in the occult, is called in to assist with the investigation.
Lionel Barrymore
as Professor Zelin
Elizabeth Allan
as Irena Borotyn
Bela Lugosi
as Count Mora
Lionel Atwill
as Inspector Neumann
Jean Hersholt
as Baron Otto
Henry Wadsworth
as Fedor Vincente
Donald Meek
as Dr. Doskil
Jessie Ralph
as Midwife
Ivan F. Simpson
as Jan
Franklyn Ardell
as Chauffeur
Leila Bennett
as Maria
June Gittelson
as Annie
