“Surveillance,” said Paul Harley. “You mean that you are more or less constantly followed?” “I do.” “And what is your impression of this follower?” “A very hazy one. To-night, as I came to your office, I have every reason to believe that someone followed me in a taxicab.” “You came in a car?” “I did.” “And a cab followed you the whole way?” “Practically the whole way, except that as my chauffeur turned into Chancery Lane, the cab stopped at the corner of Fleet Street.” “Your idea is that your pursuer followed on foot from this point?” “Such was my impression.” “H’m, quite impossible. And is this sort of thing constant, Sir Charles?” “It has been for some time past.” “Anything else?” “One very notable thing, Mr. Harley. I was actually assaulted less than a week ago within sight of my own house.” “Indeed! Tell me of this.” Paul Harley became aware of an awakening curiosity. Sir Charles Abingdon was not the type of man who is lightly intimidated. “I had been to visit a friend in the neighbourhood,” Sir Charles continued, “whom I am at present attending professionally, although I am actually retired. I was returning across the square, close to midnight, when, fortunately for myself, I detected the sound of light, pattering footsteps immediately behind me. The place was quite deserted at that hour, and although I was so near home, the worst would have happened, I fear, if my sense of hearing had been less acute. I turned in the very instant that a man was about to spring upon me from behind. He was holding in his hand what looked like a large silk handkerchief. This encounter took place in the shadow of some trees, and beyond the fact that my assailant was a small man, I could form no impression of his identity.” “What did you do?” “I turned and struck out with my stick.” “And then?” “Then he made no attempt to contest the issue, but simply ran swiftly off, always keeping in the shadows of the trees.” “Very strange,” murmured Harley. “Do you think he had meant to drug you?” “Maybe,” replied Sir Charles. “The handkerchief was perhaps saturated with some drug, or he may even have designed to attempt to strangle me.” “And you formed absolutely no impression of the man?” “None whatever, Mr. Harley. When you see the spot at which the encounter took place, if you care to do so, you will recognize the difficulties. It is perfectly dark there after nightfall.” “H’m,” mused Harley. “A very alarming occurrence, Sir Charles. It must have shaken you very badly. But we must not overlook the possibility that this may have been an ordinary footpad.” “His methods were scarcely those of a footpad,” murmured Sir Charles. “I quite agree,” said Harley. “They were rather Oriental, if I may say so.” Sir Charles Abingdon started. “Oriental!” he whispered. “Yes, you are right.” “Does this suggest a train of thought?” prompted Harley.