previously spoken to Mrs. Kettering, you remember. True, he had seen the maid just for a moment when she handed him the tickets, but his impression had been merely that of a gaunt, black-clad female. If he had been an unusually intelligent man, he might have gone so far as to say that mistress and maid were not unlike, but it is extremely unlikely that he would even think that. And remember, Ada Mason, or Kitty Kidd, was an actress, able to change her appearance and tone of voice at a moment's notice. No, no; there was no danger of his recognizing the maid in the mistress's clothing, but there was the danger that when he came to discover the body he might realize it was not the woman he had talked to the night before. And now we see the reason for the disfigured face. The chief danger that Ada Mason ran was that Katherine Grey might visit her compartment after the train left Paris, and she provided against that difficulty by ordering a dinner basket and by locking herself in her compartment."
"But who killed Ruth—and when?"
"First, bear it in mind that the crime was planned and undertaken by the two of them—Knighton and Ada Mason, working together. Knighton was in Paris that day on your business. He boarded the train somewhere on its way round the ceinture. Mrs. Kettering would be surprised, but she would be quite unsuspicious. Perhaps he draws her attention to something out the window, and as she turns to look he slips the cord round her neck—and the whole thing is over in a second or two. The door of the compartment is locked, and he and Ada Mason set to work. They strip off the dead woman's outer clothes. Mason and Knighton roll the
