The Hound of the Baskervilles needs no introduction, it's by far the most famous of Holmes' adventures and this 1939 adaptation is considered by many, myself included, to be the finest film version made; it is the quintessential Sherlock Holmes film, and the only one made that's considered to be a classic of cinema. The film was shot entirely on set and its cinematography perfectly evokes the spooky atmosphere of the fog-bound Dartmoor landscapes. The solid performances throughout, and a great supporting cast very probably makes this the best of all the fourteen films in the series…although I couldn't possibly comment.

Synopsis

The film opens on the remote Devonshire moorland, with a terrified Sir Charles Baskerville running for his life toward the safety of Baskerville Hall as a hellish hound nips at his heels. Sir Charles' old heart can't take the strain and he falls to the ground, dead, the latest victim of the curse of the Baskerville family.

Dr. James Mortimer was Sir Charles' best friend and is now worried that the new owner of Baskerville Hall, Sir Henry Baskerville, will meet the same fate as his predecessor. He goes to see Sherlock Holmes and tells the tale of the infamous 16th century Sir Hugo Baskerville who abducted a peasant girl and caused her death. He himself was then killed by a massive black hound and thereafter, the family was cursed by The Hound of The Baskervilles.

Holmes immediately dismisses the supernatural aspect of the case but is intrigued and is convinced to help. Holmes nominates Dr. Watson to escort Sir Henry to Baskerville Hall and asks Watson to keep in touch via telegram, whilst he tends to other business in town.

Watson, Sir Henry and Dr. Mortimer arrive at a fog-bound Baskerville Hall and are greeted by the incumbent servants; Barryman the butler and his wife the housekeeper, er, Mrs Barryman. Mysterious events soon unfold, with Watson and Sir Henry discovering Barryman signalling a distant light on the moor in the dead of night. They go out onto the moor to investigate, only to narrowly miss being killed. On their walk back to Baskerville Hall, they hear what appears to be the moan of a hound in the distance.

Sir Henry takes a stroll alone on the moor the next morning, and a concerned Watson soon speeds after him, meeting John Stapleton along the way and they hear an eerie howling through the fog as they stroll along together. Suddenly, they hear the voice of Beryl Stapleton, John Stapleton's sister as she shouts to warn Sir Henry, who is about to step into the deadly Grimpen Mire. Watson rushes over and the four of them exchange pleasantries before agreeing to all have supper that evening at the Stapleton's house.

That evening at supper, the choleric Mr. Frankland, local resident, exchanges barbs with the other guests before they retire to the drawing room for coffee and cigars. Sir Henry and Watson join in a séance held by Mrs. Mortimer, and in a trance, she asks “What happened that night on the moor, Sir Charles?”. The only reply is a distant howl from the moor.

Sir Henry and Beryl Stapleton spend the next few days getting to know each other before one morning he proposes to her, and she accepts. Watson is out for a stroll and interrupts this romantic scene, thankfully, and soon they're joined by an old man selling trinkets but he's seen off by Sir Henry. Watson receives an anonymous note requesting his company at a cave on the moor later that night, while John Stapleton watches Sir Henry walking on the moor.

The old man that Watson meets that night turns out to be Holmes in disguise, having been hiding out on the moor. And Watson is infuriated with him, as once again, he's been left in the dark regarding Holmes' plan. As they leave the cave, they hear a hound attacking someone and soon discover the body of an escaped convict – The Notting Hill Murderer – at the foot of an overhang, dressed in Sir Henry's old clothes. Holmes deduces that the hound attacked the convict because of Sir Henry's scent on the clothing.

Stapleton suddenly appears at the scene asking questions, whereupon Holmes announces he is going back to London in the morning as there's nothing to investigate, just “legends and rumours”.

Back at Baskerville Hall, Holmes informs Mrs Barryman that her brother, the escaped convict, is dead and that she no longer needs to leave food and clothing out for him. Holmes tells Sir Henry that the convict was behind the strange happenings on the moor and that he's no longer in danger. Holmes lets it be known that he's returning to London in the morning and before retiring for the night, Holmes spots an old family portrait on the wall and is intrigued by it.

Aboard the train to Paddington, Holmes explains to Watson that he's laid a trap for the killer by leaving Sir Henry alone, but it does put him in danger. Holmes and Watson are only giving the impression of going up to London however, and they catch the train back to Baskerville Hall when they get to Oakhampton. That evening on the moor, when the hound is finally sent to kill Sir Henry Baskerville, Holmes and Watson are waiting for it.

They kill the hound but after it wounds Sir Henry, so Holmes leaves Sir Henry in Watson's care while he goes in search of the Stapleton, now revealed as the killer. Watson takes Sir Henry to Baskerville Hall, where Stapleton suddenly appears and convinces Watson to leave Sir Henry in his care, as Holmes has asked for the doctor to join him on the moor. Stapleton is about to give Sir Henry a laced tonic, but Holmes arrives in the nick of time to stop him.

Holmes uses the old family portrait he spotted the previous night to reveal to everyone present that the true criminal is Stapleton, a long-lost cousin of the Baskervilles who hopes to claim their wealth for himself after removing the rest of the bloodline. Stapleton pulls a gun and runs out the front door onto the moor. Unlike the novel, his fate is unknown in the film but Holmes says ominously, “He won't get very far. I've posted constables along the roads and the only other way, is across the Grimpen Mire”.

The film closes with Dr. Mortimer praising Holmes, who thanks him and retires for the night – after asking Watson for “the needle”.