Suddenly he raised his head and listened, holding his breath in strained attention. He had caught the sound of distant footsteps.
In an instant he was up and had leapt to the window, where his fingers fumbled with the safety-pin that held the curtains together. No tell-tale mark of his presence must be left.
But where should he hide? The sounds were becoming more distinct every second; no escape seemed possible. There was no help for it, and he was bound to be discovered; he must put as good a face on it as he could contrive. The person approaching might, after all, not come into the library, but go back again along the passage. It might only be some one coming to see that the door to the garden was properly bolted.
These thoughts flashed through the detective's mind so quickly as to be practically simultaneous, and then almost at the same moment he realized that the footsteps did not come from the passage at all, but from under the room he was waiting in. In a flash he had grasped the full significance of this unexpected fact, and was tiptoeing across to the door.
The handle turned noiselessly in his fingers, thanks to the precaution he had taken of oiling it, and he slipped outside.
In the dark and empty passage he took to his heels and ran swiftly back to the drawing-room, nor paused till he was outside on the lawn once more. There he hung for an instant in the wind; bearings must be taken, the nearest way to the enclosed garden decided on, any dangerous reefs that lay on the way steered clear of. Then he was off again on the new tack. This led him round to the back of the holly hedge, and the arched opening by the gardeners' tool-shed.
He turned in under it and sped silently over the turf, till he found himself outside the door to the old tower. From the library window a narrow shaft of light was issuing out on to the flower-bed.
Gimblet took off his coat and threw it on to the bed. He put a foot upon one sleeve, and, stooping down, spread the other out in front of him as far as it would go. Then he stepped upon that one and twisted the coat round under him to repeat the process. In this way he arrived under the window without leaving any imprint of his boots upon the soft earth. Once there he raised himself cautiously and peered into the room.
By the writing-table, and so close to him that he could almost have touched her if they had not been separated by the glass, stood a young woman.