"Too early for town servants," Wilfrid muttered. "I have a good mind to try my own luck."

Wilfrid was by no means a timid man. He had gone through too many privations and dangers for that. With determined step, therefore, he crossed the road and laid his hand on the latch. He was not surprised to find that the catch was not down and that the door yielded to his pressure. A moment later and he was in the hall.

All the lights had been turned up. The place was flooded with a soft tender glow; pictures and flowers and statuary stood out and delighted the eye and pleased the senses. So far, whoever the intruders were, they had made hardly any attempt to disguise their presence. There was a festive air about the house, too, for the atmosphere was heavy with the smell of cigar smoke and the half-opened dining-room door showed that a snug supper party had recently met. It must have been within a few hours, for the dregs of the champagne still sparkled in the glasses. Wilfrid pressed on curious. He buttoned his overcoat about his throat in case of a surprise, and caught up an old-fashioned life-preserver from the hall table and slipped it into his pocket.

Yet nothing broke the silence; nothing indicated anything out of the common. No doubt, he surmised, there must be scores of similar scenes in the west end of London to-night, where people had come home and partaken of a hasty supper after the servants had gone to bed and then retired themselves, carelessly leaving the lights burning.

But in this particular case Wilfrid knew the lights had not been left burning. He had seen that sudden, mysterious gleam in the upper windows and the quick flash of the electrics as the whole turned to a sea of light. It was his plain duty to investigate the premises from top to bottom.

Wilfrid chose the basement, but nothing rewarded his search. All the rooms there were empty, as they were on the dining-room floor. Nor were there any strange coats or hats in the vestibule, excepting Flower's big fur wrap and soft hat, and some cloudy-looking material which Beatrice doubtless had discarded when she came in. He must look further afield and see what the next landing might reveal.

It was dangerous and difficult, but Wilfrid resolved to go through with it. He found the switches of the drawing-room lights and just turned them on long enough to enable him to see that the room was empty. He dared not try any strong illumination, for fear of arousing the suspicions of the police, who would know a great deal more about the servants' habits than he could. There appeared to be a large bedroom behind the drawing-room, looking out on the back of the house, and this Wilfrid tried cautiously. He felt sure some one was there because a long slit of light showed from under the door. The door was locked on the inside and no sound proceeded from the room save a gentle purring noise such as machinery will make when heard a long way off. Wilfrid likened it to the singing of a kettle rather than anything else. As he bent down and listened more intently he seemed to hear the murmur of voices and occasionally a suppressed groan as if from some one in pain, who was being quieted by the application of a powerful drug. A minute or two later Wilfrid knew that he was not mistaken, for from behind the locked door came a sound which was unmistakably a smothered laugh.

It was no business of his, of course, and he hesitated before he went farther. He might have paused until it was too late, had not his quickened hearing caught a sound overhead as if somebody had left the room on the next landing and was coming leisurely downstairs. Wilfrid crept back into the deep shadow of the drawing-room door and waited. It was somewhat difficult to see, for he had only the gleams of the light coming from the hall to guide him. Presently, as his eyes became more accustomed to the gloom, he saw that he was not mistaken. A man drew near with step noiseless and agile as a cat's. A peculiar perfume preceded him, a perfume which Wilfrid had not the least trouble in recognizing. It was the same strange scent he had smelt during the eventful night he had spent at Maldon Grange. He saw the stranger try the door of the bedroom; then suddenly all his restraint deserted him. His right hand shot out and he caught the little man by the throat.

"Get them to open that door," he said hoarsely. "Get them to open it at once or I'll choke the life out of you. Do you hear?"

Whether the man heeded or not he gave no sign. Wilfrid's grip was as tenacious as that of a bulldog, all his fighting instincts aroused. He felt the exhilarating sense of superior power. For the moment the man was as clay in his hands.