The Koh-i-Noor diamond had been stolen from the Tower of London and replaced by a paste copy some years earlier, by a French thief named King Victor. Chimneys is one place where it may be hidden, though many searches have not found it. King Victor was released from prison in France a few months earlier, so Battle expects he will seek to recover it. The night Cade is in France, there is a break-in at Chimneys. Virginia Revel hears the noise, and sees one or two men taking old armor apart. She and Bill Eversleigh do not catch the thief. The next night, the three wait for a second attempt; they catch M Lemoine of the Sûreté, on the track of King Victor. Battle has been waiting for him. The stolen letters appear in Cade's room. Battle realizes the thieves want him to decode the letter that points to the location of the stolen gem, because Count Stylptitch had moved it from the place where the Queen had hidden it. This is done, revealing the clue: "Richmond seven straight eight left three right". Battle follows the Richmond clue to a brick in a hidden passage, which in turn reveals a puzzling . Cade slips out to Dover, to find an address on a slip of paper given him by Boris Anchoukoff, valet to the late prince. He finds the meeting of King Victor's gang; Hiram Fish, really a Pinkerton detective on the thief's trail for his crimes in America; and the real M Lemoine tied up as a hostage.