The great detective Sherlock Holmes and his colleague Dr Watson have taken a well-earned holiday in rural Cornwall. Holmes is looking forward to walking on the moors and learning more about ancient Cornish language and culture. But it's not long before his wits are tested in a mysterious case that became known as the Cornish Horror. Some think it is the work of the devil when two people are killed and two others go mad in horrific circumstances. But can Holmes find a natural explanation?
