The late Dr. Campbell was experimenting with vampire bat blood just before his death. Colleague Paul Beecher (Beal) finds a bottle of pills among Dr. Campbell's effects and takes them home. Dr. Beecher's daughter, Betsy (Lydia Reed), accidentally substitutes the vampire blood pills for her father's migraine tablets. As a result, the kindly Dr. Beecher starts having blackouts from the pills.