Concerned for the safety of Sir Henry Baskerville, the estate's heir, Holmes sends Watson to accompany him to Baskerville Hall in Devonshire, where they encounter strange events, including a missing boot, ominous warnings, and suspicious neighbors like naturalist Jack Stapleton and his "sister" Beryl.

As Watson investigates, he discovers clues pointing to a sinister plot involving a real dog trained to terrorize the Baskervilles.

Holmes, secretly observing from a distance, reveals Stapleton's true identity as a hidden heir to the Baskerville fortune, who used the family legend to drive Sir Charles to a fatal heart attack.

In a climactic showdown, the giant hound attacks Sir Henry, but Holmes and Watson save him and expose Stapleton's plan.

The villain escapes but ultimately perishes in the treacherous Grimpen Mire, leaving Holmes and Watson to ponder the unresolved mysteries surrounding the case.