“Oh yes. Mr. and Mrs. Perrin?” “That’s right. Which flat have they taken?” “Number Nineteen. That’s the top one on the right of the stairs.” “Thank you. Do you know if they are in at present?” “Mrs. Perrin is out. I saw her go about half an hour ago. So far as I know, Mr. Perrin is in.” “Thanks. I’ll just go up and see.” French returned to the taxi. “The woman is out, but Pyke is supposed to be upstairs in Number Nineteen flat. You, Harvey, will stay in the entrance hall and watch the stairs and lift. Take him without fail if we miss him above. If the woman appears, don’t show up, but let her go in. Carter, you come upstairs with me.” Harvey strolled to the door and became immersed in the list of flat-holders, while French and Carter began to climb the stairs. There were two flats on each storey, to right and left of the flights. When they reached the first landing French pointed to a fire-escape notice. They followed the pointing hand to the back of the house along a passage between the two flats, and, silently pushing open a door fitted with panic fastenings, saw an iron staircase leading down outside of the wall from the top storey to a paved yard. “You’ll have to stay and watch that, Carter. I can manage the blighter upstairs.” For a moment French wished he had brought another man. Then he thought of how many times he had carried out arrests single-handed. There was no difficulty. A whistle would bring his two men at top speed, and if by some incredibly unlikely accident he let Pyke slip through his hands, one or other of them would certainly take him on his way down. He silently mounted the stairs to the tenth storey. No. Nineteen was the top flat, but the stairs led on to a door on to the roof. French knocked at No. Nineteen. There was no answer. In a moment he knocked again, then after waiting a few seconds, he turned the handle. The door was unlocked and French pushed it open and looked in. Through a tiny hall he could see into a living room, small and poorly furnished, and with a kitchenette in the rear. Other partially open doors from the hall led into bedrooms. So far as he could see, the place was deserted. Softly closing the outer door, he passed into the living room, and standing in its centre, looked round. Opposite him was the fireplace with a gas fire turned low. In the right wall was the window and against the left stood a table with a chair at each end. Two wicker armchairs were drawn up to the fireplace, and to the right of the door was a dresser containing crockery. Some books lay on the floor in a corner, but the centre of the room was clear of furniture. French could see everything in the room with one exception. At the side of the fireplace was a closed cupboard. Possibly this might contain something useful.