I made nothing of it, except that there seemed to be good reasons why I should get a copy at once. If _Royal Love Letters_ interested Heinrich Kristensten so deeply, it might well be that it would not be wholly without interest for me. My first care was to ring up Hecq on the official telephone and give him full particulars respecting Heinrich's sudden interest in an obscure and practically unknown volume published and forgotten seven years ago. It was quite clear that this was a hint we could not ignore, but I confess I failed to see how it helped us. But I was soon to learn more; Hecq's quick brain had seen a possibility which I had overlooked. At seven next morning, before I was out of bed, my telephone rang, and Hecq once more spoke to me. "I have been searching the papers, Sant," he said, "and I have found out something that will interest you. Listen carefully. In the _Petit Parisien_ five days ago there was an advertisement for the recovery of a lady's gold trinket. I have it here. I'll read it to you," and he read: _Perdus Ou Trouves_. Perdu Met. Opera Breloque Or. Vialet 28 Marigny R. 100. "Yes," I said, "I hear you. But what has that to do with me?" "Listen," said Hecq. "There is nobody named Vialet at that address; we found that out at once. I have had nearly fifty of my people examining every advertisement in the Paris papers issued just before Heinrich began to display an interest in _Royal Love Letters_. Now we have found out that the advertisement I have just read to you conveys in cryptogrammic form the message, `Buy _Royal Love Letters_.' It would take too long to explain it, but the paper containing that advertisement would be on sale in London the very day on which, according to Madame Gabrielle, Heinrich began to haunt the second-hand bookstalls on his peculiar quest. Rather curious, is it not?" Curious it certainly was, and once more I found myself confronted with a further enigma. Why on earth should the book be advertised in cryptogrammic form in a French newspaper? How did Heinrich come to see the advertisement, and how did he know the key to the code? No doubt the paper had accepted the innocent-looking advertisement without the slightest suspicion that it was anything but the genuine announcement it purported to be. It was impossible to overlook the coincidence between the appearance of the advertisement and Blind Heinrich's sudden deep interest in a forgotten book.