the street and stopped the traffic in order to enjoy the conversation, which left nothing to be desired in the way of free language. Dan halted idly, as a spectator, not because he wished to be one, but for the very simple reason that he could not get through the crowd into Trafalgar Square. Thrust up against one man, and wedged in by two others, and surrounded by hundreds, he grumbled at the delay, and peered over shoulders to see when the incident would end. As he did so, he suddenly in his mind's eye saw a vision of Sir Charles lying dead in the well-lighted library. While wondering why he thought of the crime at this particular moment, he became aware that a familiar scent assailed his nostrils, the scent about which he had talked to Durwin and Tenson and Laurance. Nosing like a hound, he tried to find the person from whom it emanated, and almost immediately later the man turned, and Dan found himself face to face with Marcus Penn.
CHAPTER V
MUDDY WATER
The secretary of the late Sir Charles Moon smiled irresolutely when he recognized Dan. That young gentleman, who thought Penn a weak-kneed idiot, had never taken much notice of him, but for the fact that he was perfumed with the unusual scent would not have spoken to him now. But as he looked at the lank creature with his yellow face, and scanty moustache, he guessed that he was exactly the effeminate sort of person who would use perfume. What he wished to know was why he affected this particular kind of fragrance, and whence he obtained it. To gain the information he pretended a friendliness for the man he was far from feeling. Dan, strong, virile, and self-confident, was not altogether just to Penn, who was not responsible for his pallid looks and weak character. But Halliday was not a perfect individual by any means, and had yet to learn that the weak are meant to be protected and helped instead of being despised. "You here, Mr. Penn?" said Dan, thus formal to mark the difference between them. "Yes," replied the man in his faint hesitating voice, and, as they moved out of the crowd, Halliday smelt the weird perfume more strongly than ever shaken from Penn's clothes by his movements. "I stopped to look at the accident."
"A very ordinary one," rejoined Mr. Halliday, with a shrug. "By the way, I have not seen you since the funeral of Sir Charles. What are you doing now, if I may ask?"
"I am secretary to Lord Curberry."
"Oh!" The reply gave Dan something of a shock, for he did not expect at the moment to hear his rival's name. But then the whole incident of meeting Penn and smelling the incriminating perfume was strange. Monsieur Chance had proved himself to be an actuality instead of the mythical personage Dan had believed him to be. It was certainly odd that the meeting had taken place, and odder still that Penn should prove to be the servant of Curberry. As Halliday said nothing more than "Oh!" the other man stroked his moustache and explained. "Sir John got me the post, Mr. Halliday," he said, with his shifty eyes anywhere but on Dan's inquiring face. "I was quite stranded after Sir Charles's unexpected death, and did not know where to turn for employment. As I support a widowed mother, the situation was rather serious, so I took my courage in my hands and went to Sir John. He was good enough to recommend me to Lord Curberry, and I have been with his lordship for a month, more or less."
"I congratulate you, Mr. Penn, and Lord Curberry, also. Sir Charles always said you were an excellent secretary," Dan stopped as Penn bowed his acknowledgments to the compliment, and cast a keen side glance at the man. They were walking through Trafalgar Square by this time, passing under the shadow of Nelson's Column. "Do you know what I was thinking of when behind you in the crowd yonder, Mr. Penn?" he asked abruptly, and it must be confessed rather undiplomatically, if he wished to get at the truth. "No," said the secretary, with simplicity and manifest surprise. "No, Mr. Halliday, how can I guess your thoughts?"
"I was thinking of the murder of your late employer," said Dan straightly. Penn blinked and shivered. "It's a horrible subject to think about," he remarked in a low voice. "I can scarcely get it out of my own thoughts. I suppose the sight of me reminded you of the crime, Mr. Halliday?"
"Scarcely, since I was behind you, and did not recognize you until you turned," replied Dan, calmly, and the other appeared to be surprised. "Then how-" he began, only to be cut short. "It's that scent."
"Scent!" echoed Penn nervously, but manifestly still surprised. "I don't understand exactly what you mean, Mr. Halliday. I like scent, and use much of it." Dan's lip curled. "So I perceive. But where did you get the particular scent you are using now, may I ask?" Something in his tone annoyed the secretary, for he drew himself up and halted. "I don't know why you should criticize my tastes, Mr. Halliday."
"I'm not criticizing them, and don't jump down my throat. But you reek of some strange perfume, which I last smelt-" He paused. "You cannot have smelt it anywhere," said Penn indifferently. "What do you mean by that exactly?" asked Dan with considerable sharpness. Penn resumed his walk and drew his light eyebrows together. "I am willing to explain as soon as you tell me why you speak of the scent."
"Hang it, man," rejoined Halliday, dropping into step, "any one would notice the scent and speak of it since it is so strong."
"Oh" – Penn's brow cleared-"I understand now. You have taken a fancy to the scent and wish me to get you some." Halliday was about to make an indignant denial, when he suddenly changed his mind, seeing a chance of learning something. "Well, can you get me some?"
"No," said Penn coolly; "I cannot. This is a particular perfume which comes from the Island of Sumatra. I have a cousin there who knows that I like perfumes, and he sent me a single bottle."
"Can't I buy it anywhere?"
"No, it is not to be obtained in England," said Penn curtly. "In that case," said Halliday slowly, "it is strange that I should have smelt the same perfume on the clothes of Sir Charles after his death."
"Did you?" Penn looked surprised. "That is impossible. Why, Sir Charles detested scents, and I never dared to use this one until I left him for the night."
"You used it on the night of the murder?"
"Of course. I used it every night when I left Sir Charles. On that evening he sent me away with my usual batch of letters, and was going down to the House later. I would not have seen him until the next morning, so I took the opportunity to indulge in this taste."
"Then how did Sir Charles's clothes become impregnated with it?"
"I am unable to say. Why do you ask? Surely" – Penn turned an alarmed face towards the speaker, and looked yellower than ever-"surely you do not suspect me of keeping back anything from the police likely to lead to the detection of the assassin."
"Ask yourself, Mr. Penn," said Dan coldly. "I and Inspector Tenson and Mr. Durwin smelt this particular perfume on the clothes of the dead man, and I do not mind telling you that the police consider it something of a clue."
"A clue to what? To me? It must be, since I alone possess this scent. I certainly came into the library when summoned by Mr. Durwin, and I helped to look after Sir Charles. As I was strongly perfumed with the scent it is not impossible that my employer's clothes took what, doubtless, you will call the taint. I think," ended Penn in a dignified manner, "that such is the proper explanation. You have found a mare's nest, Mr. Halliday."
"Upon my word, I believe I have," said Dan, quite good-humoredly, "but you must forgive me, Mr. Penn. Inspector Tenson agreed with me that the fly and the scent were clues."
"About the fly I know nothing," said the secretary positively, "but this scent is not to be had in England, and Sir Charles's clothes could only have gathered the fragrance from mine. If Inspector Tenson suspects me-"
"No, no, no!" interrupted Halliday quickly. "I assure you that he does not."
"He would if you told him of our meeting," retorted Penn as they passed into Piccadilly Circus, "and as
