But, in the absence of any other apparent explanation of the girl’s extraordinary decision to come to Rotterdam, Robin decided he would accept the theory that she had come about the van der Spyck letter. How like Mary, after all, he mused, self-willed, fearless, independent, to rush off to Holland on her own on a quest like this! Where would her investigations lead her? To the offices of Elias van der Spyck & Co., to be sure! Robin threw his napkin down on the table, thrust back his chair, and went off to the hotel porter to locate the address of the firm. The telephone directory showed that the offices were situated in the Oranien-Straat, about ten minutes’ walk from the hotel, in the business quarter of the city round the Bourse. Robin glanced at the clock. It was twenty minutes to ten. The principals, he reflected, were not likely to be at the office before ten o’clock. It was a fine morning and he decided to walk. The hotel porter gave him a few simple directions: the gentleman could not miss the way, he said; so Robin started off, hope high in his breast of getting a step nearer to the elucidation of the mystery of the library at Harkings. A brisk walk of about ten minutes through the roaring streets of the city brought him to a big open square from which, he had been instructed, the Oranien-Straat turned off. He was just passing a large and important-looking post-office—he remarked it because he looked up at a big clock in the window to see the time—when a man came hastily through the swing-door and stopped irresolutely on the pavement in front, glancing to right and left as a man does who is looking for a cab. At the sight of him Robin could scarcely suppress an expression of amazement. It was Mr. Jeekes. CHAPTER XXII. THE MAN WITH THE YELLOW FACE In a narrow, drowsy side street at Rotterdam, bisected by a somnolent canal, stood flush with the red-brick sidewalk a small clean house. Wire blinds affixed to the windows of its ground and first floors gave it a curious blinking air as though its eyes were only half open. To the neat green front door was affixed a large brass plate inscribed with the single name: “Schulz.” A large woman, in a pink print dress with a white cloth bound about her head, was vigorously polishing the plate as, on the morning following her departure from London, Mary Trevert, Dulkinghorn’s letter of introduction in her pocket, arrived in front of the residence of Mr. William Schulz. Euan MacTavish had, on the previous evening, seen her to her hotel and had then—very reluctantly, as it seemed to Mary—departed to continue his journey to The Hague, his taxi piled high with white-and-green Foreign Office bags, heavily sealed with scarlet wax. Mary Trevert approached the woman, her letter of introduction, which Dulkinghorn, being an unusual person, had fastened down, in her hand. “Schulz?” she said interrogatively. “_Nicht da_,” replied the woman without looking up from her rubbing.