It was Mrs. Bolstreath who carried Lillian upstairs in her stout arms, for when Penn made his brusque announcement the girl fainted straight away, which was very natural considering the horror of the information. Dan remained behind to tell the secretary that he was several kinds of fool, since no one but a superfine ass would blurt out so terrible a story to a delicate girl. Not that Penn had told much, for Lillian had become unconscious the moment her bewildered brain grasped that the father she had left a few hours earlier in good health and spirits was now a corpse. But he told more to Dan, and mentioned that Mr. Durwin was in the library wherein the death had taken place.

“Mr. Durwin? Who is Mr. Durwin?” asked Dan trying to collect his sense, which had been scattered by the dreadful news.

“An official from Scotland Yard; I told you so after dinner,” said Penn in an injured tone; “he came to see Sir Charles by appointment at nine o’clock and found him a corpse.”

“Sir Charles was alive when we left shortly after eight,” remarked Dan sharply; “at a quarter-past eight, to be precise. What took place in the meantime?”

“Obviously the violent death of Sir Charles,” faltered the secretary.

“What evidence have you to show that he died by violence?” asked Halliday.

“Mr. Durwin called in a doctor, and he says that Sir Charles has been poisoned,” blurted out Penn uneasily. “I believe that woman — Mrs. Brown she called herself — poisoned him. She left the house at a quarter to nine, so the footman says, for he let her out, and —”

“It is impossible that a complete stranger should poison Sir Charles,” interrupted Dan impatiently; “she would not have the chance.”

“She was alone with Sir Charles for thirty minutes, more or less,” said Penn tartly; “she had every chance and she took it.”

“But how could she induce Sir Charles to drink poison?”

“She didn’t induce him to drink anything. The doctor says that the scratch at the back of the dead man’s neck —”

“Here!” Dan roughly pushed the secretary aside, becoming impatient of the scrappy way in which he detailed what had happened. “Let me go to the library for myself and see what has happened. Sir Charles can’t be dead.”

“It’s twelve o’clock now,” retorted Penn, stepping aside, “and he’s been dead quite three hours, as the doctor will tell you.”

Before the man finished his sentence, Dan, scarcely grasping the situation, so rapidly had it evolved, ran through the hall towards the back of the spacious house, where the library was situated. He dashed into the large and luxuriously furnished room and collided with a police officer, who promptly took him by the shoulder. There were three other men in the room, who turned from the corpse they were looking at when they heard the noise of Halliday’s abrupt entrance. The foremost man, and the one who spoke first, was short and stout and arrayed in uniform, with cold grey eyes, and a hard mouth.

“What’s this — what’s this?” he demanded in a raucous voice. “Who are you?”

“My name is Halliday,” said Dan hurriedly. “I am engaged to Miss Moon and we have just returned from the theatre to hear — to hear —” He caught sight of Moon’s body seated in the desk-chair and drooping limply over the table. “Oh, it is true, then! He is dead. Good heavens! Who murdered him?”

“How do you know that Sir Charles has been murdered?” asked the officer sternly.

“Mr. Penn, the secretary, told me just now in the hall,” said Dan, shaking himself free of the policeman. “He blurted it out like a fool, and Miss Moon has fainted. Mrs. Bolstreath has taken her upstairs. But how did it come about? Who found the body, and —”

“I found the body,” interrupted one of the other men, who was tall and calm-faced, with a bald head and a heavy iron-grey moustache, perfectly clothed in fashionable evening-dress, and somewhat imperious in his manner of speaking. “I had an appointment with Sir Charles at nine o’clock and came here to find him, as you now see him”— he waved his hand towards the desk —“the doctor will tell you how he died.”

“By poison,” said the third man, who was dark, young, unobtrusive and retiring in manner. “You see this deep scratch on the back of the neck. In that way the poison was administered. I take it that Sir Charles was bending over his desk and the person who committed the crime scratched him with some very sharp instrument impregnated with poison.”

“Mrs. Brown!” gasped Dan, staring at the heavy swollen body of his late guardian, who, only a few hours back, had been in perfect health.

The three men glanced at one another as he said the name, and even the policeman on guard at the door looked interested. The individual in uniform spoke with his cold eyes on Dan’s agitated face. “What do you know of Mrs. Brown, Mr. Halliday?” he demanded abruptly.

“Don’t you know that a woman of that name called here?”

“Yes. The secretary, Mr. Penn, told us that Miss Moon induced her father to see a certain Mrs. Brown, who claimed that her son had been drowned while working on one of the steamers owned by Sir Charles. You saw her also I believe?”

“I was in the hall when Miss Moon went to induce her father to see the poor woman. That was about a quarter past eight o’clock.”

“And Mrs. Brown — as we have found from inquiry — left the house at a quarter to nine. Do you think she is guilty?”

“I can’t say. Didn’t the footman see the body — that is, if Mrs. Brown committed the crime — when he came to show her out? Sir Charles would naturally ring his bell when the interview was over, and the footman would come to conduct her to the door.”

“Sir Charles never rang his bell!” said the officer, drily. “Mrs. Brown passed through the entrance hall at a quarter to nine o’clock, and mentioned to the footman — quite unnecessarily, I think — that Sir Charles had given her money. He let her out of the house. Naturally, the footman, not hearing any bell, did not enter this room, nor — so far as any one else is concerned — did a single person. Only when Mr. Durwin —”

“I came at nine o’clock,” interrupted the bald-headed man imperiously, “to keep my appointment. The footman told Mr. Penn, who took me to Sir Charles. He knocked but there was no answer, so he opened the door and we saw this.” He again waved his hand towards the body.

“Does Mr. Penn know nothing?” asked Halliday, doubtfully.

“No,” answered the other. “Inspector Tenson has questioned him carefully in my presence. Mr. Penn says that he brought Sir Charles his spectacles from the dining-room before you left for the theatre with the two ladies, and then was sent to his own room by his employer to write the usual letters. He remained there until nine o’clock when he was called out to receive me, and we know that Mr. Penn speaks truly, for the typewriting girl who was typing Sir Charles’s letters to Mr. Penn’s dictation, says that he did not leave the room all the time.”

“May I look at the body?” asked Dan approaching the desk, and on receiving an affirmative reply from Durwin, bent over the dead.

The corpse was much swollen, the face indeed being greatly bloated, while the deep scratch on the nape of the neck looked venomous and angry. Yet it was a slight wound to bring about so great a catastrophe, and the poison must have been very deadly and swift; deadly because apparently Sir Charles had no time to move before it did its work, and swift because he could not even have called for assistance, which he surely would have done had he been able to keep his senses. Dan mentioned this to the watchful doctor, who nodded.

“I can’t say for certain,” he remarked cautiously, “but I fancy that snake-poison has been used. That will be seen to, when the post-mortem is made.”

“And this fly?” Halliday pointed to an insect which was just behind the left ear of the dead man.

“Fly!” echoed Inspector Tenson in surprise, and hastily advancing to look. “A fly in November. Impossible! Yet it is a fly, and dead. If not,” he swept the neck of the corpse with his curved hand, “it would get away. H’m! Now I wonder what this means? Get me a magnifying glass.”

There was not much difficulty in procuring one, as such an article lay on the desk itself; being used, no doubt, by Sir Charles to aid his failing sight when he examined important documents. Tenson inspected the fly and removed it — took it to a near electric light and examined it. Then he came back and examined the place behind the left ear whence he had removed it.

“It’s been gummed on,” he declared in surprise — a surprise which was also visible in the faces of the other men; “you can see the glistening spot on the skin, and the fly’s legs are sticky.” He balanced the fly on his little finger as he spoke. “I am sure they are sticky, although it is hard to say with such a small insect. However,” he carefully put away the fly in a silver match-box, “we’ll have this examined under a more powerful glass. You are all witnesses, gentlemen, that a fly was found near the wound which caused Sir Charles Moon’s death.”

“And the scent? What about the scent?” Dan sniffed as he spoke and then bent his nose to the dead man. “It seems to come from the clothes.”

“Scent!” echoed Durwin sharply, and sniffed. “Yes, I observed that scent. But I did not take any notice of it.”

“Nor did I,” said the doctor. “I noticed it also.”

“And I,” followed on the Inspector, “and why should we take notice of it, Mr. Halliday? Many men use scent.”

“Sir Charles never did,” said Dan emphatically; “he hated scents of all kinds even when women used them. He certainly would never have used them himself. I’ll swear to that.”

“Then this scent assumes importance.” Durwin sniffed again, and held his aquiline nose high. “It is fainter now. But I smelt it very strongly when I first came in and looked at the body. A strange perfume it is.”

The three men tried to realise the peculiar odour of the scent, and became aware that it was rich and heavy and sickly, and somewhat drowsy in its suggestion.

“A kind of thing to render a man sleepy,” said Dan, musingly.

“Or insensible,” said Inspector Tenson hastily, and put his nose to the dead man’s chin and mouth. He shook his head as he straightened himself. “I fancied from your observation, Mr. Halliday, that the scent might have been used as a kind of chloroform, but there’s no smell about the face. It comes from the clothes,” he sniffed again; “yes, it certainly comes from the clothes. Did you smell this scent on Mrs. Brown?” he demanded, suddenly.

“No, I did not,” admitted Halliday promptly, “otherwise I should certainly have noted it. I have a keen sense of smell. Mrs. Bolstreath and Lil — I mean Miss Moon — might have noticed it, however.”

At that moment, as if in answer to her name, the door opened suddenly and Lillian brushed past the policeman in a headlong entrance into the library. Her fair hair was in disorder, her face was bloodless, and her eyes were staring and wild. Behind her came Mrs. Bolstreath hurriedly, evidently trying to restrain her. But the girl would not be restrained, and rushed forward scattering the small group round the dead, to fling herself on the body.

“Oh, Father, Father!” she sobbed, burying her face on the shoulder of her dearly-loved parent. “How awful it is. Oh, my heart will break. How shall I ever get over it. Father! Father! Father!”

She wept and wailed so violently that the four men were touched by her great grief. Both Mr. Durwin and Inspector Tenson had daughters of their own, while the young doctor was engaged. They could feel for her thoroughly, and no one made any attempt to remove her from the body until Mrs. Bolstreath stepped forward. “Lillian, darling. Lillian, my child,” she said soothingly, and tried to lead the poor girl away.

But Lillian only clung closer to her beloved dead. “No! No! Let me alone. I can’t leave him. Poor, dear Father — oh, I shall die!”

“Dear,” said Mrs. Bolstreath, raising her firmly but kindly, “your father is not there, but in heaven! Only the clay remains.”

“It is all I have. And Father was so good, so kind — oh, who can have killed him in this cruel way?” She looked round with streaming eyes.

“We think that a Mrs. Brown —” began the Inspector, only to be answered by a loud cry from the distraught girl.

“Mrs. Brown! Then I have killed Father! I have killed him! I persuaded him to see the woman, because she was in trouble. And she killed him — oh, the wretch — the — the — oh — oh! What had I done to her that she should rob me of my dear, kind father?” and she cried bitterly in her old friend’s tender arms.

“Had you ever seen Mrs. Brown before?” asked Durwin in his imperious voice, although he lowered it in deference to her grief.

Lillian winced at the harsh sound. “No, no! I never saw her before. How could I have seen her before? She said that her son had been drowned, and that she was poor. I asked Father to help her, and he told me he would. It’s my fault that she saw my father and now”— her voice leaped an octave —“he’s dead. Oh — oh! my father — my father!” and she tried to break from Mrs. Bolstreath’s arms to fling herself on the dead once more.

“Lillian darling, don’t cry,” said Dan, placing his hand on her shoulder.

“You have not lost the dearest and best of fathers!” she sobbed violently.

“Your loss is my loss,” said Halliday in a voice of pain, “but we must be brave, both you and I.” He associated himself with her so as to calm her grief. “It’s not your fault that your dear father is dead.”

“I persuaded him to see Mrs. Brown. And she — she — she —”

“We can’t say if this woman is guilty, as yet,” said Durwin hastily, “so do not blame yourself, Miss Moon. But did you smell any scent on this Mrs. Brown?”

Lillian looked at him vacantly and shook her head. Then she burst once more into hard and painful sobbing, trying again to embrace the dead man.

“Don’t ask her any questions, Sir,” said Halliday, in a low voice to Mr. Durwin, “you see she is not in a fit state to reply. Lillian,” he raised her up from her knees and gently but firmly detached her arms from the dead. “My darling, your father is past all earthly aid. We can do nothing but avenge him. Go with Mrs. Bolstreath and lie down. We must be firm.”

“Firm! Firm — and Father dead!” wailed Lillian. “Oh, what a wretch that Mrs. Brown must be to kill him! Kill her, Dan — oh, make her suffer! My good, kind father, who — who — oh”— she flung herself on Dan’s neck —“take me away! take me away!” and her lover promptly carried her to the door.

Mrs. Bolstreath, who had been talking hurriedly to Inspector Tenson, came after the pair and took the girl from Dan. “She must lie down and have a sleeping-draught,” she said softly. “If the doctor will come —”

The doctor was only too glad to come. He was a young man beginning to practise medicine in the neighbourhood, and had been hurriedly summoned in default of an older physician. The chance of gaining a new and wealthy patient was too good to lose, so he quickly followed Mrs. Bolstreath as she led the half-unconscious girl up the stairs. Dan closed the door and returned to the Inspector and the official from Scotland Yard. The former was speaking.

“Mrs. Bolstreath did not smell any perfume on Mrs. Brown,” he was saying, “and ladies are very quick to notice such things. Miss Moon also shook her head.”

“I don’t think Miss Moon was in a state of mind to understand what you were saying, Mr. Inspector,” said Halliday, drily. “However, I am quite sure from my own observation that Mrs. Brown did not use the perfume. I would have noticed it at once, for I spotted it the moment I examined the body.”

“So did I,” said Durwin once more; “but I thought Sir Charles might have used it. You say he did not, therefore the scent is a clue.”

“It does not lead to the indictment of Mrs. Brown, however, Sir,” said Tenson thoughtfully, “since she had no perfume of that sort about her. But she must have killed Sir Charles, for she was the last person who saw him alive.”

“She may come forward and exonerate herself,” suggested Dan after a pause, “or she may have left her address with Sir Charles.”

“I have glanced through the papers on the desk and can find no address,” was the Inspector’s reply; “yet, if she gave it to him, it would be there.”

Durwin meditated, then looked up. “As she was the mother of the man in Sir Charles’s employment who was drowned,” he said in his harsh voice, and now very official in his manner, “in the offices of the company who own the steamers — Sir Charles was a director and chief shareholder, I understand from his secretary Mr. Penn — will be found the drowned man’s address, which will be that of his mother.”

“But I can’t see what motive Mrs. Brown had to murder Sir Charles,” remarked Dan in a puzzled tone.

“We’ll learn the motive when we find Mrs. Brown,” said Tenson, who had made a note of Durwin’s suggestion. “Many people think they have grievances against the rich, and we know that the late Sir Charles was a millionaire. He doubtless had enemies — dangerous enemies.”

“Dangerous!” The word recalled to Dan what Moon had said at the dinner-table when Lillian had playfully offered him a penny for his thoughts. “Sir Charles at dinner said something about dangerous people.”

“What did he say?” asked the Inspector and again opened his note-book.

Dan reported the conversation, which was not very satisfactory, as Moon had only spoken generally. Tenson noted down the few remarks, but did not appear to think them important. Durwin, however, was struck by what had been said.

“Sir Charles asked me here to explain about a certain gang he believed was in existence,” he remarked.

“What’s that, Sir?” asked the Inspector alertly. “Did he tell you anything?”

“Of course he didn’t. How could he when he was dead when I arrived?” retorted Durwin with a frown. “He simply said that he wished to see me in my official capacity about some gang, but gave me no details. Those were to be left until I called here. He preferred to see me here instead of at my office for reasons which he declared he would state when we met in this room.”

“Then you think that a gang —”

“Mr. Inspector,” interrupted Durwin, stiffly, “I have told you all that was said by the deceased. Whether the gang is dangerous, or what the members do, or where they are, I cannot say. Have you examined these windows?” he asked suddenly, pointing to three French-windows at the side of the room.

“Yes,” said Tenson promptly, “as soon as I entered the apartment I did so. They are all locked.”

“And if they were not, no one could enter there,” put in Dan quickly. “Outside is a walled garden and the wall is very high with broken bottles on top. I suppose, Mr. Durwin, you are thinking that someone may have come in to kill Sir Charles between the time of Mrs. Brown’s departure and your coming?”

“Yes,” assented the other sharply, “if the perfume is a clue, Mrs. Brown must be innocent. Penn, as we know from the statement of the typewriter girl, was in his room all the time, and the servants have fully accounted for themselves. We examined them all — the Inspector and I did, that is — when you were at the theatre,” he waved his hand with a shrug. “Who can say who is guilty?”

“Well,” said Tenson, snapping the elastic-band round his note-book and putting it into his pocket, “we have the evidence of the fly and the perfume.”

“What do you think about the fly?” asked Dan, staring.

“I don’t know what to think. It is an artificial fly, exquisitely made and has been gummed on the dead man’s neck behind the left ear. The assassin must have placed it there, since a man would scarcely do such a silly thing himself. Why it was placed there I can’t say, any more than I can guess why Sir Charles was murdered, or who murdered him. The affair is a complete mystery, as you must admit.”

Before the inquest and after the inquest, more people than the three men who had held the discussion in the presence of the dead, admitted that the affair was a mystery. In fact the evidence at the inquest only plunged the matter into deeper gloom. Tenson, acting on Darwin’s advice, sought the office of the tramp-steamer company — the Universal Carrier Line — in which the late Sir Charles was chief shareholder and director, to learn without any difficulty the whereabouts of Mrs. Brown, the mother of the drowned man. She proved to be an entirely different person to the woman who had given the name on the fatal night, being lean instead of stout, comparatively young instead of old, and rather handsome in an elderly way in place of being wrinkled and worn with grief. She declared that she had never been near Moon’s house on the night of the murder or on any other night. Mrs. Bolstreath, Lillian, the footman, and Dan all swore that she was not the Mrs. Brown who had sought the interview with Sir Charles. Therefore it was argued by everyone that Mrs. Brown, taking a false name and telling a false story, must have come to see Moon with the deliberate intention of murdering him. Search was made for her, but she could not be found. From the moment she passed out of the front door she had vanished, and although a description was published of her appearance, and a reward was offered for her apprehension, no one came forward to claim it. Guilty or innocent, she was invisible.

Inspector Tenson did not speak at the inquest of the gang about which Sir Charles had intended to converse with Mr. Durwin, as it did not seem to have any bearing on the case. Also, as Durwin suggested, if it had any bearing it was best to keep the matter quiet until more evidence was forthcoming to show that such a gang — whatever its business was — existed. Then the strange episode of the fly was suppressed for the same reason. Privately, Tenson informed Dan that he would not be surprised to learn that there was a gang of murderers in existence whose sign-manual was a fly, real or artificial, and instanced another gang, which had been broken up some years previously, who always impressed the figure of a purple fern on their victims. But the whole idea, said Tenson, was so vague that he thought it best to suppress the fact of the artificial fly on the dead man’s neck. “If there’s anything in it,” finished the Inspector, “there’s sure to be other murders committed, and the fly placed on the victim. We’ll wait and see, and if a second case occurs, we’ll be sure that such a gang exists and will collar the beasts. Best to say nothing, Mr. Halliday.”

So he said nothing, and Dan said nothing, and Durwin, who approved of the necessary secrecy, held his tongue. Of course there was a lot of talk and many theories as to who had murdered the millionaire, and why he had been murdered in so ingenious a manner. The post-mortem examination proved that Moon had died of snake-poison administered through the scratch on the neck, and the circumstantial evidence at the inquest went to show that he must have been taken unawares, while bending over his desk. Some people thought that Mrs. Brown was innocent because of the absence of the perfume; others declared she must be guilty on account of her false name and false story, and the fact that Moon was found dead a quarter of an hour after she left the house. No doubt, the circumstantial evidence was very strong, but it could not be said positively that the woman was guilty, even though she did not appear to defend her character.

So the jury thought, for they brought in the only possible verdict twelve good and lawful men could bring in: “Wilful murder against some person or persons unknown,” and there the matter ended for sheer want of further evidence. The affair was a mystery and a mystery it remained.

“And will until the Day of Judgment!” said Tenson, finally.