The Hound of the Baskervilles

In London, 1889, Sherlock Holmes and John Watson are visited by a Dr James Mortimer, asking for the aid of Holmes, beginning by reading him a legend that has run in the Baskerville family since the time of the English Civil War, when Sir Hugo Baskerville kidnapped a farmer's daughter. When the girl escaped Hugo pursued her, swearing a curse upon himself in his mad rage. Hugo's companions witnessed the girl dead of fear and Hugo killed by a demonic hound that is said to have haunted Dartmoor ever since, causing the premature death of many Baskervilles. Mortimer further explains that his friend, the philanthropic baronet Sir Charles Baskerville, who took the legend very seriously and had a weak heart, had resided at Baskerville Hall after amassing a fortune in South Africa. When the baronet's body was found in a yew alley, with an expression of horror on his face, the death was attributed to cardiac arrest; however Mortimer had noticed large canine paw prints near the body. Sir Charles had been the eldest of three Baskerville brothers and Sir Henry, the Canadian son of the deceased second brother, is Sir Charles' heir. The rather immoral third brother, Rodger, died of yellow fever in South America in 1876. Mortimer, the executor of Sir Charles' will, fears it might not be wise to bring Sir Henry to Dartmoor in light of the possible supernatural dangers.
Though Holmes dismisses the legend as a fairy tale he meets Sir Henry when the new baronet arrives in London. It transpires that strange things are already happening to Sir Henry; one of his old boots has been stolen, he has received an anonymous letter warning him against the moor, and someone has been following him in a hansom. Mortimer reveals that Sir Henry's inheritance is about
£740,000 (equivalent to £82,000,000 in 2025); in view of these high stakes Holmes asks Watson to act as Sir Henry's bodyguard and to investigate things on Dartmoor. Upon arriving in Dartmoor, Watson, Mortimer and Sir Henry learn that Selden, a convicted murderer, has escaped from Princetown Prison and is loose on the moor. At Baskerville Hall they are introduced to John and Eliza Barrymore, the married butler and housekeeper. Watson sends detailed accounts of his investigations to Holmes, particularly focusing on the local residents. The Stapleton siblings stand out; Jack is over-friendly, drops hints about the hound, and warns Watson against attempting to cross the dangerous Grimpen Mire. His sister, Beryl, without his knowledge, repeatedly tries to get Sir Henry to flee back to London. Another neighbour, Mr Frankland, is a perpetual busybody and troublemaker, including threatening to bring a lawsuit against Dr Mortimer for excavating nearby barrows. Sir Henry falls in love with Beryl Stapleton, though her brother strongly objects to the romance.
Barrymore repeatedly sends candlelight signals to someone on the moor. Following Barrymore one night, Watson and Sir Henry discover that Selden is Mrs Barrymore's younger brother and that she and her husband have been leaving food out for him. During an unsuccessful attempt to catch Selden Watson sees a strange man standing on a tor.

Watson and Sir Henry learn from Barrymore that Frankland's estranged daughter, Laura Lyons, had once written to Sir Charles. After a failed attempt to interrogate Laura, Watson investigates the man on the tor and discovers that it is Holmes, who has been investigating in secret to hide his direct involvement. Holmes reveals that Jack Stapleton is the murderer, and Beryl is actually his wife, abused and forced into posing as his sister; however, Holmes does not have enough proof to convince the authorities. Holmes and Watson fear they hear Sir Henry fleeing from a baying hound, and falling from a cliff; they find the dying man is Selden; Barrymore had given Selden Sir Henry's discarded clothes, and Stapleton's hound, having been set on the trail with Sir Henry's stolen boot, had confused the scent. At Baskerville Hall, Holmes reveals to Watson that the portrait of Sir Hugo Baskerville bears a remarkable resemblance to Stapleton.
Holmes decides to use an unwitting Sir Henry as bait; he orders him to visit Stapleton that evening, and then walk across the moor on foot. Holmes and Watson then pretend to leave for London, but instead hide near Stapleton's house with Inspector Lestrade of Scotland Yard. Despite thick fog, they manage to kill the hound when Stapleton unleashes it after Sir Henry. They go to Stapleton's house to find he has bound his wife to a column and vanished into the mire, where he is presumed to have drowned.
After Sir Henry and Dr Mortimer depart on a sea voyage, to repair the baronet's shattered nerves, Holmes explains to Watson that Stapleton was really Rodger Baskerville II, the secret son of Sir Charles' youngest brother. A physical and spiritual throwback to Sir Hugo, Rodger II had bought a savage black hound and painted it with phosphorus to make it look diabolical; either by fright or direct attack, he hoped the dog would remove all the other heirs so that he could inherit the Baskerville fortune. He had promised Laura to help her divorce her estranged husband and then marry her himself and thus perasuaded her to lure Sir Charles out of his house on the night of the murder. Intending to save Sir Henry, Beryl had sent the anonymous letter to him to thwart her husband's further schemes. Holmes remarks that he considers Stapleton one of his most cunning adversaries.