Sherlock Holmes summons his old friend, Dr. Watson, to work with him again on what starts out as a rather mundane investigation. But it is not long before the mystery grows more complex expanding to international proportions. It also attracts the attention of Sherlock Holmes' nemesis, Professor Moriarty. Sherlock Holmes must fall back on several of the secret coding systems that he has used in the past and also don a couple of different disguises to stay one step ahead of a growing list of criminals standing in the way of his solving the case. Holmes and Watson sojourn for a fortnight in Sweden to gather critical clues. Surprisingly, a couple of Holmes' old cases that were not completely solved previously, reappear at awkward times to complicate the present case. Some of Holmes' associates suffer as well (and with even one horrific death) during the denouement of the case and Holmes is injured by Colonel Sebastian Moran at a critical juncture. Do Holmes and Watson prevail? Well, yes and no. And thereby hangs a tale.