Dr. Bird's voice was cut short by the sound of a pistol shot from the roof, followed by two others. The Irishwoman dropped Bolton and slumped into a sitting position and screamed lustily. Bolton and Dr. Bird, with the two operatives at their heels, raced for the roof. Before they reached it another volley of shots rang out, these sounding from the rear of the building. They made their way to the upper floor and found a ladder running to a skylight in the roof. At the foot of the ladder stood one of Carnes' party. "What is it, Williams?" demanded Bolton. "I don't know, Chief. Carnes and the other two went up there, and then I heard shooting. My orders were to let no one come down the ladder." As he spoke, Carnes' head appeared at the skylight. "It's the right place, all right, Doctor," he called. "Come on up, the shooting is all over." * * * * * Dr. Bird mounted the ladder and stepped out on the roof. Set on one edge was a large piece of apparatus, toward which the scientist eagerly hastened. He bent over it for a few moments and then straightened up. "Where is the operator?" he asked. Carnes silently led the way to the edge of the roof and pointed down. Dr. Bird leaned over. At the foot of the fire escape he saw a crumpled dark heap, with a secret service operative bending over it. "Is he dead, Olmstead?" called Carnes. "Dead as a mackerel," came the reply. "Richards got him through the head on his first shot." "Good business," said Dr. Bird. "We probably could never have secured a conviction and the matter is best hushed up anyway. Bolton, have two of your men help me get this apparatus up to the Bureau. I want to examine it a little. Have the body taken to the morgue and shut up the press. Find out which room the chap occupied and search it, and bring all his papers to me. From a criminal standpoint, this case is settled, but I want to look into the scientific end of it a little more." "I'd like to know what it was all about, Doctor," protested Bolton. "I have followed your lead blindly, and now I have a housebreaking without search-warrant and a killing to explain, and still I am about as much in the dark as I was at the beginning." "Excuse me, Bolton," said Dr. Bird contritely; "I didn't mean to slight you. Admiral Clay wants to know about it and so does Carnes, although he knows me too well to say so. As soon as I have digested the case I'll let you know and I'll go over the whole thing with you." * * * * * A week later Dr. Bird sat in conference with the President in the executive office of the White House. Beside him sat Admiral Clay, Carnes and Bolton. "I have told the President as much as I know, Doctor," said the Admiral, "and he would like to hear the details from your lips. He has fully recovered from his malady and there is no danger of exciting him."