The Adventure of the Tall Man

When searching through Conan Doyle's papers, Hesketh Pearson, a biographer of his, came across a plan for an unwritten story. As Richard Lancelyn Green notes, "there is no evidence to show that it is by [Conan Doyle] and strong internal evidence to suggest that it's not". Various authors have attempted to complete the story (named "The Adventure of the Tall Man" by Peter Haining) and put it alongside the canon. Some are very close to Doyle's plot, others including variations. However no 'official' completion has been made.