Anthony Horowitz captures the essence of the Sherlock Holmes genre. Dr. Watson is back with Sherlock Holmes at 221 B Baker Street while Mary Watson is off to care for an ailing child. A fine arts dealer, Edmund Carstairs, comes to Holmes for help-- a strange man with a flat hat is stalking him very publicly. Carstairs relates that man is a ring leader for a Boston crime gang who's ire he provoked when he attempted to get the culprits who stole his four valuable landscape paintings. The murder investigation of the Boston criminal drags the pair deeper into intrigue.