It is later December in 1889. A battered old hat is the only clue to the mysterious disappearance of a Christmas lunch. But when Sherlock Holmes lays out the facts of the case, Watson finds them incorrigible. A startling revelation at 221B Baker Street adds the dimension of a jewel theft, which sends the detective duo on a tour around central London where they encounter two of the three hazards on the bucket-list of life that a gentleman must never do. The clues that they uncover brings them back to Baker Street for a seemingly infeasible conclusion.