In the meantime Bernard Boyne had been startled by the ringing of the bell, yet in the full knowledge that Mrs. Felmore could hear nothing. That secret alarm had, as a matter of fact, been installed with his own hands about two months before, with its switch concealed in the upstairs room. On hearing it, he instantly flung off his white cloak and dashed headlong down the stairs. In the hall, however, he halted and burst out laughing. "Fool you are, Bernard!" he exclaimed aloud to himself. "Yes, you are getting more nervous every day!" The reason of this was because close to the front door sat Mrs. Felmore’s black cat, waiting to be let out for the night. "Ah, pussy!" he exclaimed. "So it is you who ran silently down the stairs and set off the gong, eh?" And, opening the door, he let out the cat, saying: "Out you go, Jimmy, and don’t do it again." Then he reascended the stairs to the locked room, perfectly satisfied with the solution of what a few moments before had caused him very considerable alarm. No intruder would be tolerated in that dingy house—the house of great mystery. He carried in his hand a small bottle of meat extract which he had taken from the sideboard in the parlour, and was fully satisfied that it was the cat who had set off the alarm. As Gerald and Marigold sat side by side in the train, they could not converse because of the noise, but at Earl’s Court, where they changed, the girl for Wimbledon Park and her lover bound in the opposite direction, Marigold halted on the platform, and said: "I feel worried about auntie, Gerald. There’s something wrong in that house. Don’t you think so?" "Frankly, I do," was the young man’s reply. "That he sets an alarm when he visits the mysterious person concealed in that locked room is in itself a most remarkable feature of the affair, which is one we must certainly probe to the bottom." "But Mr. Boyne is such a nice man. Everyone speaks so well of him. In all Hammersmith I don’t think he has a single enemy, save those who are jealous of his local popularity. And there are always such." "As I’ve said before, Marigold, the men who are deep schemers always take care to establish a high reputation locally. This Mr. Boyne has, no doubt, done so with some ulterior motive." "And that motive we mean to find out," said the girl decisively. "We will," he said, in a hard voice. "I feel confident that we are on the track of some very sensational affair." "Who can be the person who is hiding?" "Ah! that remains to be seen. It is evidently someone who dare not show his face—not only in the light of day, but even at night." "But why does Mr. Boyne wear that hideous robe with slits for the eyes?" asked Marigold, bewildered, as they walked to the stairs. "At present, I can’t imagine. But we shall know the truth very soon, never fear," the young man replied. And then, lifting his hat politely, he shook her hand, and they parted after a very adventurous evening.