The door opened. "Yes, sir, the party in question has got an office there right enough, but he hasn't been at Duke House for some time--some three weeks, the porter said. He took the office late in October, and for a time he was there, on and off, a good deal. The porter don't quite know what his business is, but as far as he knows he gives him a good character. His office is right at the very top of the house, the only one let on that floor." An unpleasant little trickle of doubt came over Sir Angus's mind. When he had first read the typewritten letter, he had doubted very much if there was such a building in existence as Duke House, Piccadilly. Then, after he had heard that the place was there, after, as a matter of fact, it had been recalled to his memory by his subordinate, he had fallen back on the belief that there would be no person of the name of Fernando Apra to be found in Duke House. He now fell back on a third position. Doubtless this extraordinary letter had been written by some enemy of the man Apra who wished to cause him the unpleasantness of a visit from the police. After a few moments' thought Sir Angus Kinross proposed something which none of the three people there knew to be a most surprising departure from his usual rule. "What would you say, Lord St. Amant, if you and I were to go up there now, to Duke House--accompanied, of course, by two of my men? That, at any rate, would put an end to Mrs. Pavely's suspense. If she doesn't mind doing so, Mrs. Pavely and her friend can wait here, in my private room." To Lord St. Amant the proposal seemed a most natural one. "I think that's a very good idea!" he exclaimed, and then he saw Katty's eyes fixed imploringly on his face. Why, of course----! He beckoned to Sir Angus, and the two men walked over to the big window overlooking the Embankment. "If it would not be greatly out of order," he muttered, "I think it might be a good thing if Mrs. Winslow--that is Mrs. Pavely's friend--were to go with us to Duke House. She might be useful--she has known Mr. Godfrey Pavely all her life." Sir Angus looked very much surprised. "Of course she could come," he said hesitatingly. "Mrs. Winslow? I didn't realise that this lady is Mrs. Winslow. Didn't I see a letter written to her by Mr. Godfrey Pavely? She has some odd Christian name--if it's the person I have in my mind." "Her Christian name is Katty," said Lord St. Amant quickly. "Yes, that was it--'My dear Katty.' I remember now. It was a letter about an investment, written on the 30th of December, if I'm not mistaken. Certainly she can come with us. I have my car downstairs--she could drive in my car, and wait in it while we make the investigation." The two came back to where the ladies were sitting, silently waiting. "I have suggested to Sir Angus that it might be useful if Mrs. Winslow came with us--and you too, my dear Laura, if you desire to do so, of course."