Sherlock Holmes comes out of retirement in 1912 and travels to America to once again confront his arch rival Moriarty, who is poised to take over the United States, one piece at a time. As fishing with baited lines begins to give way to the age of steam powered trawlers dragging of the ocean bottom with massive nets, the Professor has plans of cornering the global fish market. Holmes, Watson, six brothers, and a little girl from Provincetown are the only things in his way.