“Miss Trevert,” he said, when the manager, a blond and suave Swiss, had presented himself, “has been to the dentist and has been rather upset by the gas. Would you get one of the maids to help her up to her room and in the meantime telephone for a doctor. If there is an English doctor in Rotterdam, I should prefer to have him!” The manager clicked in sympathy. He despatched a lady typist and a chambermaid to help Mary out of the car. “For a doctor,” he said, “it ees fortunate. We ’ave an English doctor staying in ze hotel now—a sheep’s doctor. He is in ze lounge. Eef you come, _hein?_” The “sheep’s doctor” proved to be a doctor off one of the big liners, a clean-shaven, red-faced, hearty sort of person who readily volunteered his services. As Robin was about to follow him into the lift, the manager stopped him. “Zere was a shentleman call to see Mees Trevert,” he said, “two or three time ’e been ’ere ... a Sherman shentleman. ’E leave ’er a note ... will you take it?” Greatly puzzled, Robin Greve balanced in his hands the letter which the manager produced from a pigeon-hole. Then he tore open the envelope. DEAR MISS TREVERT [he read], I was extremely sorry to miss you this morning. Directly I received your message I called at your hotel, but, though I have been back twice, I have not found you in. Circumstances have arisen which make it imperative that I should see you as soon as possible. This is _most urgent_. I will come back at four o’clock, as I cannot get away before. Do not leave the hotel _on any pretext_ until you have seen me and Dulkinghorn’s letter as identification. You are in _grave danger_. The note was signed “W. Schulz.” “H’m,” was Robin’s comment; “he writes like an Englishman, anyway.” He ascertained the number of Mary Trevert’s room and went up to her floor in the lift. He waited in the corridor outside the room for the doctor to emerge, and lit a cigarette to while away the time. It was not until he had nearly finished his second cigarette that the doctor appeared. The doctor hesitated on seeing Robin. Then he stepped close up to him. Robin noticed that his red face was more flushed than usual and his eyes were troubled. “What’s this cock-and-bull story about gas you’ve put up to the manager?” he said bluntly in a low voice. “The girl’s been doped with chloroform, as well you know. You’ll be good enough to come downstairs to the manager with me ...” Robin took out his note-case and produced a card. “That’s my name,” he said. “You’ll see that I’m a barrister ...” “Well?” said the doctor in a non-committal voice after he had read the card.