Adventures of Sherlock Holmes; or, Held for Ransom was a 1905 American silent film directed by J. Stuart Blackton for Vitagraph Studios. It was the second film based on Arthur Conan Doyle's Sherlock Holmes stories, following the 1900 Mutoscope trick film Sherlock Holmes Baffled, and is usually regarded as the first attempt to film a "serious" Holmes adaptation. The scenario was by Theodore Liebler based on elements of Conan Doyle's novel The Sign of the Four.