"The Problem of Thor Bridge" is a Sherlock Holmes short story by Arthur Conan Doyle collected in The Case-Book of Sherlock Holmes (1927). It was first published in 1922 in The Strand Magazine (UK) and Hearst's International The story was adapted for the Sherlock Holmes 1968 BBC series with Peter Cushing, but the episode is now lost. The story was also dramatised in 1991 in Granada TV's series Sherlock Holmes starring Jeremy Brett with Daniel Massey as Neil Gibson, Celia Gregory as Maria Gibson, and Catherine Russell as Grace Dunbar. A similar framing method is used in Murder, She Wrote, Season 8, Episode 17 (1992) "To the Last Will I Grapple with Thee".