The Memoirs of Sherlock Holmes - The Crooked Man
A few months after Watson's marriage, Holmes visits Watson to help with the end of a case.
Story: Colonel James Barclay and his wife Nancy were heard fighting. They have never had a disagreement. The coachman tried to break down the door to the room they were fighting in. It was locked from the inside but the key was no where in the room. The colonel was lying on the floor in a pool of his own blood and the wife was fainted on the couch.
Result: Henry Wood was competing with Colonel Barclay for Nancy's hand at the time. During the Indian Mutiny, Henry volunteered to go out for help, Barclay gives Henry directions straight into an ambush. He was taken and tortured (thus deformed.)
Henry saw Nancy the night of the incident and followed her home. He saw her fighting with her husband and climb in through the window. The Colonel went into shock and collapsed at the sight of Henry