THE FINAL PROBLEM by Sir Arthur Conan Doyle

Holmes had escaped three separate murder attempts after a visit from Professor Moriarty, who warned Holmes to withdraw from his pursuit of justice against him to avoid any regrettable outcome.
Holmes has been tracking Moriarty and his agents for months and is on the brink of snaring them all and delivering them to the dock. Moriarty is the criminal genius behind a highly organised and extremely secret criminal force and Holmes will consider it the crowning achievement of his career if he can defeat Moriarty. Moriarty is out to thwart Holmes's plans and is well capable of doing so, for he is, as Holmes admits, the great detective's intellectual equal.
After being deceived to leave Holmes alone, Watson rushes back to the Reichenbach Falls but finds no one there, although he does see two sets of footprints going out onto the muddy dead end path with none returning. There is also a note from Holmes, explaining that he knew Watson was deceived to leave him alone, - and that he is about to fight Moriarty, who has graciously given him enough time to pen this last letter. Watson sees that towards the end of the path there are signs that a violent struggle has taken place and there are no returning footprints. It is all too clear Holmes and Moriarty have both fallen to their deaths down the gorge while locked in mortal combat...

[First published in the Strand Magazine, Dec. 1893, with 9 illustrations by Sidney Paget.]