Tab fixed him with an unwavering glance. “You don’t suppose--” he began, but thought better of it. “I don’t suppose that your friend Mr. Carver will not come in search of you, that was what you were going to say, but believe me, Mr. Carver will never find you. In the first place he would not come here, for nobody knows that you are here. He didn’t even suspect that I was your visitor last night.” “Have you a clock in your room?” said Tab, a light dawning on him. The other frowned. “In my bedroom, at the hotel?” he was surprised into saying. “You haven’t!” said Tab triumphantly. “Good old Carver! He asked you the time when he was talking on the telephone, didn’t he? And you replied. He knew you were the man who came into the flat. He knew that when he called you up, you would be fully dressed and have a watch in your pocket.” “Oh,” said the other blankly, and then: “He came to see me this morning, damn him! It was to discover whether there was a clock in the room eh?” he grinned, but there was no humour in those bared teeth. “He doesn’t know you are here, anyway,” he said. “Goodbye, Tab. Do you remember how you tried to make a reporter of me, and how I used to sit at the office studying crime? Well, I found a new trick in those cuttings, and I have been waiting years to put it into practice.” No other word he spoke, but took something from his pocket, it was a reel of stout cotton. Then from his waistcoat he produced a new pin, and with great care and solemnity tied the thread to the end of the pin, Tab watching him intently. And all the time he was working, Rex Lander was humming a little tune, as though he were engaged in the most innocent occupation. Presently, he stuck the point of the pin in the centre of the table, and pulled at it by the thread he had fastened. Apparently he was satisfied. He unwound a further length of cotton and when he had sufficient, he threaded the key upon it, carrying it well outside the door. The end he brought back into the vault, pushing it through one of the air-holes. Then he closed the door carefully. He had left plenty of slack for his purpose and Tab heard the click of the lock as it was fastened and his heart sank. He watched the door fascinated and saw that Lander was pulling the slack of the cotton through the air-hole. Presently the key came in sight under the door. Higher and higher came the sagging line of cotton and the key rose until it was at the table’s level, slid down the taut cotton and came to rest on the table. Tighter drew the strain on the thread, and presently the pin came out, passed through the hole in the key, leaving it in the exact centre of the table. Tab watched the bright pin as it was pulled across the floor and through the ventilator. That was the secret of the pin!