Sir Borotyn, a prominent Prague resident, is discovered murdered in his home, with all indications pointing to a vampiric assault. The victim's friend, Baron Otto, and the physician who analyzes the body, are certain that the vampire is either the mysterious Count Mora or his daughter. Receiving little help from the law, occult expert Professor Zelen is sought to assist with their investigation.

• Metro-Goldwyn-Mayer
• Lionel Barrymore
• Elizabeth Allan
• Bela Lugosi
• Lionel Atwill
• Jean Hersholt
• Henry Wadsworth
• Donald Meek
• Jessie Ralph