In the 17th century, the arrogant, cruel Hugo Baskerville (David Oxley) brutalizes a servant and prepares to turn the man's daughter over to his equally depraved companions, but she escapes. When he catches up with the girl in a ruined abbey, he kills her and then is attacked and killed himself by a huge hound that is never seen. The audience then learns that this story is being told in flashback to Sherlock Holmes (Peter Cushing) and Dr. Watson (Andre Morell) by Dr. Richard Mortimer (Francis DeWolff). He was the physician and friend to the late Sir Charles Baskerville, who recently died -- apparently of fright -- on the Devonshire moors near that same ruined abbey. Holmes is very skeptical, but agrees to meet Sir Henry Baskerville (Christopher Lee), who has just arrived in London to claim the estate. Sir Henry is cold and aloof but becomes convinced he's in danger when he's almost bitten by a tarantula. Holmes insists that he not go to Baskerville Hall alone, so Holmes sends Watson to Devonshire with Sir Henry.In Devonshire, Sir Henry and Watson learn that an escaped convict, Selden, is at large on the moor. Watson meets local Bishop Frankland (Miles Malleson), and later on the moor, Baskerville's neighbors, Stapleton (Ewen Solon) and his daughter, Cecile (Marla Landi). Watson is almost trapped in one of the many bogs that dot the moors, but he escapes. Later, leaving Sir Henry stricken with a mild heart attack at the hall, Watson ventures again onto the moors, and to his surprise, discovers Sherlock Holmes there. Holmes has been hiding and watching for developments. They hear the howl of the hound, and are too late to prevent the huge beast from killing a man they take for Sir Henry. But back at Baskerville Hall, they find Sir Henry alive and well: the dead man was the convict Selden, dressed in some old clothes of Sir Henry's. At the ruined abbey, they find evidence that a strange rite has been performed. When Holmes visits Frankland for information, he learns that someone has stolen the bishop's tarantula. (He's an amateur naturalist.) Meanwhile, near Baskerville Hall, Sir Henry meets Cecile, and they are attracted to one another. Holmes, Mortimer and Stapleton descend into a disused tin mine in search of evidence, but a cave-in almost traps Holmes. That evening, when Sir Henry goes to meet Cecile on the moors, he learns that she actually hates him, and that the hound is now on his trail. Holmes and Watson arrive almost too late to save him, but Holmes kills the hound and reveals it's an ordinary, if large, dog in a mask. The villain is a descendant of Sir Hugo's from the wrong side of the sheets; he and his daughter were determined to use the legend of the Hound to kill those standing between them and Baskerville Hall. No movie version of Sir Arthur Conan Doyle's most famous novel follows its source very closely, and this colorful Hammer film is no exception. An extra killer is added, events are compressed, and even the novel's most famous line -- they were the tracks of an enormous hound! -- is omitted. The film also suffers at times from a budget too low for its ambitions and by extraneous elements aimed at making it more like a Hammer movie, such as the unexplained rite. However, the movie has a brisk pace and particularly strong characters. Lee, initially icy and arrogant -- perhaps to remind us of Sir Hugo -- thaws into a likable person romantic enough to fall in love, atypically for Lee. Andre Morell is one of the most solid