Addy Zhuang is "Sherlock's Secretary," the bank employee tasked with responding to all of the letters addressed to Sherlock Holmes. One day, his life is turned upside-down when two bank robbers burst into his office and steal three letters addressed to Sherlock Holmes. The police conclude that this is all some pointless prank, but Addy can't shake the suspicion that something more sinister was behind the theft. When a true crime reporter gets interested in the case, Addy joins her in an investigation that leads to a cast of colorful characters, and a long-buried secret involving a forgotten Sherlock Holmes television movie and the "Great Erasure" at the BBC. It's a humorous romp celebrating Sherlock Holmes fandom and a twisty mystery that's not just a whodunit, but also a whydunit.