The Adventures of Sherlock Holmes: The Boscombe Valley Mystery recap

James McCarthy is arrested after his father, Charles, is found dying beside Boscombe Pool. Witnesses saw James follow him, and James admits to a quarrel, but Alice Turner asks Holmes to prove her childhood friend innocent. At the scene Holmes finds signs that a third man was present. He learns that Charles had known Alice's wealthy father, John Turner, in Australia and had long held unexplained power over him. Turner confesses that he once led a criminal gang and that Charles had recognized and blackmailed him. When Charles demanded that James marry Alice, Turner killed him with a stone. Holmes retains Turner's confession but uses the physical evidence to clear James, sparing the terminally ill Turner a public trial. James is acquitted, Turner dies soon afterward, and James and Alice are left free of the coercion that caused the crime.

Holmes and Watson travel to Boscombe Valley after Inspector Lestrade asks for help with the killing of farmer Charles McCarthy. The evidence points to Charles's son James, who was seen following him toward Boscombe Pool and admits that they quarrelled shortly before he found his father dying. Alice Turner, James's childhood companion, believes him innocent. Holmes examines the ground and concludes that another man, lame and carrying a blunt weapon, was present. James has concealed a failed marriage, but that secret explains his dispute with his father rather than the murder. Holmes connects the victim's last words and the tracks to Alice's father, John Turner. Turner confesses that he and Charles knew each other in Australia, where Turner had been a robber. Charles later recognized him and used the secret to blackmail him, finally demanding a marriage between James and Alice. Turner killed Charles with a stone to end the coercion. Gravely ill, he signs a confession that Holmes reserves in case it is needed. Holmes's evidence secures James's acquittal; Turner dies months later, and James and Alice remain unaware of the full truth.

Holmes identifies John Turner as the man who killed Charles McCarthy. In Australia, Turner had led a band of robbers, and McCarthy later recognized him in England and used that knowledge to extort land and money. When McCarthy tried to force a marriage between James and Alice, Turner struck him with a stone beside Boscombe Pool. The victim's final reference to a rat was an unfinished attempt to say Ballarat, pointing back to Australia. Turner gives Holmes a written confession. Because Turner is gravely ill, Holmes does not immediately expose him; instead, he keeps the confession available in case James is convicted. Holmes's analysis of the physical evidence is enough to undermine the prosecution, and James is acquitted. Turner dies several months later, while James and Alice are free to build a life together without knowing every detail of their fathers' history.