"That's it," he said. "The murderer was here with her. When we came, he struck her a blow with his fist and gagged her so that we should not hear her moans." "But how did he get away?" "Through here . . . look . . . there is a passage connecting all the attics on the first floor." "And from there?" "From there, he went down the stairs of one of the other dwellings." "But he would have been seen!" "Pooh, who knows? The creature's invisible. Never mind! Send your men to look. Tell them to search all the attics and all the ground-floor lodgings." He hesitated. Should he also go in pursuit of the murderer? But a sound brought him back to the girl's side. She had got up from the floor and a dozen pieces of gold money had dropped from her hands. He examined them. They were all French. "Ah," he said, "I was right! Only, why so much gold? In reward for what?" Suddenly, he caught sight of a book on the floor and stooped to pick it up. But the girl darted forward with a quicker movement, seized the book and pressed it to her bosom with a fierce energy, as though prepared to defend it against any attempt to take hold of it. "That's it," he said. "The money was offered her for the book, but she refused to part with it. Hence the scratches on the hands. The interesting thing would be to know why the murderer wished to possess the book. Was he able to look through it first?" He said to Waldemar: "My dear count, please give the order." Waldemar made a sign to his men. Three of them threw themselves on the girl and, after a hard tussle, in which the poor thing stamped, writhed and screamed with rage, they took the volume from her. "Gently, child," said Lupin, "be calm. . . . It's all in a good cause. . . . Keep an eye on her, will you? Meanwhile, I will have a look at the object in dispute." It was an odd volume of Montesquieu's _Voyage au temple de Guide_, in a binding at least a century old. But Lupin had hardly opened it before he exclaimed: "I say, I say, this is queer! There is a sheet of parchment stuck on each right hand page; and those sheets are covered with a very close, small handwriting." He read, at the beginning: "_Diary of the Chevalier GILLES DE MALRÊCHE, French servant to His Royal Highness the Prince of ZWEIBRUCKENVELDENZ, begun in the Year of Our Lord 1794._" "What! Does it say that?" asked the count. "What surprises you?" "Isilda's grandfather, the old man who died two years ago, was called Malreich, which is the German form of the same name." "Capital! Isilda's grandfather must have been the son or the grandson of the French servant who wrote his diary in an odd volume of Montesquieu's works. And that is how the diary came into Isilda's hands." He turned the pages at random: "_15 September, 1796._ His Royal Highness went hunting. "_20 September, 1796._ His Royal Highness went out riding. He was mounted on Cupidon."