The Sign of Three

As Lestrade fumes over his constant inability to convict the Waters gang of bank robbers, Holmes prepares for his role as best man at Mary and John's wedding. His speech, initially bizarre, turns out to be a moving tribute to his friend whilst he also contributes two anecdotes of recent cases, both unsolved. The first concerns a young guardsman whose life John saved after he was the victim of a 'locked room' attempted murder. The second involves a man who uses the identities of the recently deceased to date different women. As he looks around the wedding party, Holmes suddenly realizes their connected solutions, which also involve Watson's former commanding officer, disfigured war hero Major Sholto.