American professor John Holden arrives in London for a conference on parapsychology only to discover that the colleague he was supposed to meet was killed in a freak accident the day before. It turns out that the deceased had been investigating a cult lead by Dr. Julian Karswell. Though a skeptic, Holden is suspicious of the devil-worshiping Karswell. Following a trail of mysterious manuscripts, Holden enters a world that makes him question his faith in science.

Genial shopkeeper Philip has to endure the constant nagging of a shrewish wife while he secretly yearns for a pretty young stenographer. When the henpecking gets to be too much, Philip murders his wife and manages to make her death look like an accident. A ruthless blackmailer and a low-key detective both discover Philip's secret, and he has to decide which of them poses the more dangerous threat.

Greedy heirs wait in a mansion for a rich cat lover to die, only to learn her cats come first.

On his uncle's death Sir Henry Baskerville returns from Canada to take charge of his ancestral hall on the desolate moors of Devonshire, and finds that Sherlock Holmes is there to investigate the local belief that his uncle was killed by a monster hound that has roamed the moors since 1650, and is likely to strike again at Sir Henry.