For the first time in its one-hundred-and-twenty-five-year history, the Arthur Conan Doyle Estate has authorized a new Sherlock Holmes novel. A fine art dealer named Edmund Carstairs visits Sherlock Holmes and Dr. John Watson to beg for their help. He is being menaced by a strange man in a flat cap - a wanted criminal who seems to have followed him all the way from America. In the days that follow, his home is robbed, his family is threatened. And then the first murder takes place.