"Let us walk on," suggested Boyne, turning purposely towards Knightsbridge. "There are some people trying to overhear our conversation." Galtier saw a man and two women who had halted close by, probably attracted by the loud tones in which they were conversing. Strange conversations go on in the London streets at night, as every police constable knows. The night-world of London is an amazing world, of which the honest go-to-bed-early citizen knows nothing. One half the world of London is ignorant of what the other half does o’ nights. They moved on past the taxi shelter towards Knightsbridge, which was in the opposite direction to Upper Brook Street. "I think you are certainly not fair to madame," Boyne said very quietly to the girl. "She, out of her own generous heart—for no better-hearted woman ever lived—sought you out because she felt that she had treated you unkindly. Of course, I do not know the real facts, but on the face of it I think you, mademoiselle, treated your late mistress with ingratitude. I say this," he went on, "in a perfectly friendly spirit. You may have formed some unfounded suspicion regarding poor Mr. Martin’s death. Why, I don’t know." "Because I heard the truth from madame’s own lips." "Some distorted words half overheard, I suppose," he laughed. "My dear mademoiselle, it is always very dangerous to interfere with the death of anybody, because here in England there is such a thing as a law of slander, and of libel—criminal libel, which means that those who make false accusations may be committed to prison. Therefore, before you go further, I advise you to consult a solicitor. He will no doubt advise you." "We will see the police first," declared Galtier. "I have not the slightest objection," laughed Boyne. "If you think it will avail you, go to Scotland Yard. That is the head office of the Criminal Investigation Department, but"—and he paused—"but I tell you this, Monsieur, if either of you make any accusations against madame or myself, we shall at once prosecute you—and further, if you escape back to France, we will follow you there and prosecute you. Here, in England, we will not permit foreigners to come over and give the police a lot of trouble for nothing. So make whatever statement you like, but don’t forget you will have to substantiate it with witnesses—otherwise you’ll probably both find yourselves in prison. That’s all I have to say. Good-night!" And, turning abruptly upon his heel, the master-criminal walked back towards Hyde Park Corner, leaving mademoiselle and her companion utterly perplexed. Bernard Boyne, as he hurried up Park Lane on his return to Upper Brook Street, muttered to himself: "I’ve given them something to think over! They’ll hesitate—and while they hesitate, we must act. It would have been fatal for them to have met Ena—and especially to-night—_of all nights_!" Ten minutes later he was back in Ena Pollen’s room, where she was sitting with Lilla.