Larsan had threatened Darzac as he had threatened Mathilde—with the same weapon, and the same threats. He wrote Darzac urgent letters, declaring himself ready to deliver up the letters that had passed between him and his wife, and to leave them for ever, if he would pay him his price. He asked Darzac to meet him for the purpose of arranging the matter, appointing the time when Larsan would be with Mademoiselle Stangerson. When Darzac went to Epinay, expecting to find Ballmeyer or Larsan there, he was met by an accomplice of Larsan’s, and kept waiting until such time as the “coincidence” could be established. It was all done with Machiavellian cunning; but Ballmeyer had reckoned without Joseph Rouletabille. * * * * * Now that the Mystery of The Yellow Room has been cleared up, this is not the time to tell of Rouletabille’s adventures in America. Knowing the young reporter as we do, we can understand with what acumen he had traced, step by step, the story of Mathilde Stangerson and Jean Roussel. At Philadelphia he had quickly informed himself as to Arthur William Rance. There he learned of Rance’s act of devotion and the reward he thought himself entitled to for it. A rumour of his marriage with Mademoiselle Stangerson had once found its way into the drawing-rooms of Philadelphia. He also learned of Rance’s continued attentions to her and his importunities for her hand. He had taken to drink, he had said, to drown his grief at his unrequited love. It can now be understood why Rouletabille had shown so marked a coolness of demeanour towards Rance when they met in the witnesses’ room, on the day of the trial. The strange Roussel-Stangerson mystery had now been laid bare. Who was this Jean Roussel? Rouletabille had traced him from Philadelphia to Cincinnati. In Cincinnati he became acquainted with the old aunt, and had found means to open her mouth. The story of Ballmeyer’s arrest threw the right light on the whole story. He visited the “presbytery”—a small and pretty dwelling in the old colonial style—which had, indeed, “lost nothing of its charm.” Then, abandoning his pursuit of traces of Mademoiselle Stangerson, he took up those of Ballmeyer. He followed them from prison to prison, from crime to crime. Finally, as he was about leaving for Europe, he learned in New York that Ballmeyer had, five years before, embarked for France with some valuable papers belonging to a merchant of New Orleans whom he had murdered. And yet the whole of this mystery has not been revealed. Mademoiselle Stangerson had a child, by her husband,—a son. The infant was born in the old aunt’s house. No one knew of it, so well had the aunt managed to conceal the event. What became of that son?—That is another story which, so far, I am not permitted to relate. * * * * *