Abigail Danforth's companion, Maude Cunningham, begs her to find the killer who gunned down her beloved fiancé in San Francisco's Chinatown. Abigail follows the advice of her mentor, Sir Arthur Conan Doyle, and begins the process of logical detection. With the young writer, Jack London, as her guide, Miss Danforth takes her investigation to the denizens of the Barbary Coast.