She had some vague recollection of having seen one of the men before, and though she remained apparently languidly interested in the business of the platform, she was racking her brains to think who he was or where she had seen him. It was recently, she was certain. Suddenly she leaned forward, and her smooth brow contracted in a frown. Yes--she was nearly certain. He had an overcoat and a silk hat on now, but when she last saw him he had been a bare-headed, frock-coated clerk in the advertisement office of the _Daily Wire_. The frown disappeared and she dropped back. But behind the placid face an alert brain was working. Had the man followed her, or was it a mere coincidence? Was he a detective? With an effort of will she stilled the apprehension in her breast. Her confidence reasserted itself. Even if he were a detective, what had she to fear? She had merely delivered a cipher advertisement over the counter. It was unlikely that it would be read by others than the person for whom it was intended. Even if it were, there was nothing in it to incriminate her. Her lips parted in a contemptuous smile. "I don't believe he is a detective at all," she murmured. All doubts on the subject, however, were set at rest as the express began to glide out of the station. As though taken unawares by its departure, the man hastily shook hands with his friend and sprinted for the train, swinging himself into the woman's compartment with a gasp of relief. "Phew," he said. "A narrow shave that," and then, as if realising the sex of his companion, "I--I beg your pardon. I hope the carriage is not reserved. If so, I will change." She smiled winningly at him. "No, don't disturb yourself, I beg. It would be a pity after all the trouble you have taken--to catch the train." Detective-Inspector Blake was not by any means dull. His immobile features gave no sign that he was half inclined to believe the woman was gibing him. "Now, what the devil does she mean by that?" he said, under his breath. He bowed in acknowledgment of her courtesy, and drawing a paper from his pocket unfolded it. "And how is the charming Mr. Foyle?" said the Princess, speaking with a soft drawl. "I do hope he is still well." This time Blake was taken unawares. He dropped the paper as though it were red-hot, and the woman laughed. A moment later he was ashamed of himself. She had trapped him into a tacit admission that he was a detective. A surprised denial of acquaintance with Mr. Foyle might have ended in an apology on her part for a mistake. Well, it was too late now. "So you are a colleague of Mr. Foyle's?" she went on, and though her voice was soft there was a trace of mockery in it. "He is charmingly considerate to send you to look after me. I was desolated to think that I should have to take such a long journey by myself."