He beckoned to Joe, who had halted a couple of paces in the rear, and, mounting the steps, the two of them followed the constable into the building. He led the way up the staircase to Marsden's room, where, in response to his knock, the Inspector himself opened the door. Over his shoulder Colin caught sight of another man in plain clothes, who was standing with his back to the fire. "Come along in, doctor," exclaimed the detective. "I've got some one here you ought to know--Inspector Ainsworth, of the Investigation Department. He has been doing some rather useful work for you during the last twenty-four hours." Colin shook hands with his new acquaintance, a stout, gray-haired individual, who eyed him with considerable interest. "And this is our friend Bates, eh?" continued Marsden, turning a sharp glance on Joe. "But where's Miss Seymour? I thought you were going to bring her with you." "You had better hear what I've got to tell you straight away," said Colin. "Miss Seymour never came to Shadwell this morning. I went up to her flat just before midday, and I found out from the girl next door that someone had called for her in a car at eight o'clock with a letter from her lawyer in Cornwall." "What, Penwarren?" broke out Marsden. "Impossible! Why, he's seriously ill down at Helston." "I know," said Colin. "I sent him a wire at once and I've just got the answer. The letter was a forgery. "And Miss Seymour?" demanded Marsden quickly. "She went away in the car and nothing has been heard of her since." Marsden took a couple of paces across the room, and then turned to his colleague. "I blame myself for this, Ainsworth," he said. "I ought to have had the place watched." "That's so," assented the other. "All the same, I don't think there's any harm done. It's plain enough what they're after, but if they want to bring it off they'll have to take her abroad. You can't work that sort of gadget in England." There was a short pause, which was broken by Marsden. "You had better get hold of Graham immediately. Tell him that the girl's been kidnapped, and that an attempt will probably be made to smuggle her out of the country. They're already on the lookout for Cooper, so it will only be a matter of sending another message." Giving a curt nod, Ainsworth strode to the door, and, with an abrupt change in his manner, Marsden addressed himself to Colin. "I am sorry this has happened," he said, "especially as it's partly my fault. I wish to God you could have let me know sooner." "I came along immediately," retorted Colin, "but you weren't here." For a moment Marsden hesitated. "Have you any idea who Miss Seymour really is?" he asked slowly. Colin stared at him. "What do you mean?" he demanded. "She is the granddaughter of Professor Carter, and the heiress to over a quarter of a million of money." If the Professor himself had suddenly appeared through the doorway Colin's amazement could hardly have been more complete.