Sir Karell Borotyn appears to have been killed by Count Mora, a vampire who prowled around his castle. One year later, Irena, Karell’s daughter, is haunted by the vampire and will be his next victim… unless Professor Zelen can avoid it.
Graverobbers open the grave of the Wolfman and awake him. He doesn’t like the idea of being immortal and killing people when the moon is full, so he tries to find Dr. Frankenstein, in the hopes that the Dr. can cure him, but Frankenstein is dead and only his Monster is alive and this one wants to live, not to die like the Wolfman.
Movie star Shelah Fane is seeing wealthy Alan Jaynes while filming in Honolulu, Hawaii, but won’t marry him without consulting famed psychic Tanaverro first. Tanaverro confronts her about the unsolved murder of fellow film star Denny Mayo three years earlier, and she decides to reject Jaynes’ proposal. When Shelah is found shot to death in her beach-front pavilion, Charlie Chan of the Honolulu Police investigates.
In 19th century England, a noted brain surgeon rescues a former student from being hanged on a false conviction for murder, and spirits him away to an ancient, repurposed abbey far in the countryside. There, he connives his pupil into assisting him in mapping the functions of the various parts of the human brain, using living subjects who are under a terrible animation-suspending drug called “black sleep”. Subsequently, the student, along with the daughter of one of the subjects, discover that most of these subjects have survived but are being kept in a dungeon-like cellar, in various stages of derangement…