"What do you mean?" asked Dr. van Heerden.

"I merely repeat the words of the dead man," answered Beale, "heart failure!"

He picked up from the table the leather case which the doctor had taken from his pocket. There were four little phials and one of these was uncorked.

"Digitalis!" he read. "That shouldn't kill him, doctor."

He looked at van Heerden thoughtfully, then picked up the phial again. It bore the label of a well-known firm of wholesale chemists, and the seal had apparently been broken for the first time when van Heerden opened the tiny bottle.

"You have sent for the police?" Beale asked the agitated manager.

"Oui, m'sieur--directly. They come now, I think."

He walked to the vestibule to meet three men in plain clothes who had just come through the swing-doors. There was something about van Heerden's attitude which struck Beale as strange. He was standing in the exact spot he had stood when the detective had addressed him. It seemed as if something rooted him to the spot. He did not move even when the ambulance men were lifting the body nor when the police were taking particulars of the circumstances of the death. And Beale, escorting the shaken girl up the broad staircase to a room where she could rest and recover, looked back over his shoulder and saw him still standing, his head bent, his fingers smoothing his beard.

"It was dreadful, dreadful," said the girl with a shiver. "I have never seen anybody--die. It was awful."

Beale nodded. His thoughts were set on the doctor. Why had he stood so motionless? He was not the kind of man to be shocked by so normal a phenomenon as death. He was a doctor and such sights were common to him. What was the reason for this strange paralysis which kept him chained to the spot even after the body had been removed?

The girl was talking, but he did not hear her. He knew instinctively that in van Heerden's curious attitude was a solution of Predeaux's death.

"Excuse me a moment," he said.

He passed with rapid strides from the room, down the broad stairway and into the palm-court.

Van Heerden had gone.

The explanation flashed upon him and he hurried to the spot where the doctor had stood.

On the tessellated floor was a little patch no bigger than a saucer which had been recently washed.

He beckoned the manager.

"Who has been cleaning this tile?" he asked.

The manager shrugged his shoulders.

"It was the doctor, sare--so eccentric! He call for a glass of water and he dip his handkerchief in and then lift up his foot and with rapidity incredible he wash the floor with his handkerchief!"

"Fool!" snapped Beale. "Oh, hopeless fool!"

"Sare!" said the startled manager.

"It's all right, M'sieur Barri," smiled Beale ruefully. "I was addressing myself--oh, what a fool I've been!"

He went down on his knees and examined the floor.

"I want this tile, don't let anybody touch it," he said.

Of course, van Heerden had stood because under his foot he had crushed the digitalis tablet he had taken from the phial, and for which he had substituted something more deadly. Had he moved, the powdered tablet would have been seen. It was simple--horribly simple.

He walked slowly back to where he had left Oliva.

What followed seemed ever after like a bad dream to the girl. She was stunned by the tragedy which had happened under her eyes and could offer no evidence which in any way assisted the police in their subsequent investigation, the sum of which was ably set forth in the columns of the _Post Record_.

"The tragedy which occurred in the Palm-Court of the Grand Alliance Hotel yesterday must be added to the already long list of London's unravelled mysteries. The deceased, a man named Jackson, has been staying at the hotel for a week and was on the point of departure for Canada. At the last moment Dr. van Heerden, who was assisting the unfortunate man, discovered that Jackson was no other than the wanted man in the Millinborn murder, a crime which most of our readers will recall.

"Dr. van Heerden stated to our representative that the man had represented that he was a friend of the late John Millinborn, but was anxious to get to Canada. He had produced excellent credentials, and Dr. van Heerden, in a spirit of generosity, offered to assist him. At the eleventh hour, however, he was struck with the likeness the man bore to the published description of the missing man in the Millinborn case, and was on the point of telegraphing to the authorities at Liverpool, when he discovered that Jackson had missed the train.

"The present tragedy points to suicide. The man, it will be remembered, collapsed, and Dr. van Heerden rendered first aid, administering to the man a perfectly harmless drug. The post-mortem examination reveals the presence in the body of a considerable quantity of cyanide of potassium, and the police theory is that this was self-administered before the collapse. In the man's pocket was discovered a number of cyanide tablets.

"'I am satisfied,' said Dr. van Heerden, 'that the man already contemplated the deed, and when I voiced my suspicions in the palm-court he decided upon the action. The presence in his pocket of cyanide--one of the deadliest and quickest of poisons--suggests that he had the project in his mind. I did not see his action or, of course, I should have stopped him!'"

Oliva Cresswell read this account in her room two nights following the tragedy and was struck by certain curious inaccuracies, if all that the doctor had told her was true.

Mr. Beale read the account, smiled across the table grimly to the bearded superintendent of the Criminal Investigation Department.

"How does that strike you for ingenuity?" he said, pushing the paper over the table.

"I have read it," said the other laconically, "I think we have sufficient evidence to arrest van Heerden. The tile from the Grand Alliance shows traces of digitalis."

Beale shook his head.

"The case would fall," he said. "What evidence have you? We did not confiscate his medicine-case. He might have dropped a tablet of digitalis by accident. The only evidence you could convict van Heerden on is proof that he brought with him cyanide tablets which he slipped into Predeaux's pocket. No, we can prove nothing."

"What is your theory in connection with the crime?"

"I have many theories," said Mr. Beale, rising and pacing the room, "and one certainty. I am satisfied that Millinborn was killed by Doctor van Heerden. He was killed because, during the absence of Mr. Kitson in the village, the doctor forced from the dying man a secret which up till then he had jealously preserved. When Kitson returned he found his friend, as he thought, _in extremis_, and van Heerden also thought that John Millinborn would not speak again. To his surprise Millinborn did speak and van Heerden, fearful of having his villainy exposed, stabbed him to the heart under the pretext of assisting him to lie down.

"Something different occurred at the Grand Alliance Hotel. A man swoons, immediately he is picked up by the doctor, who gives him a harmless drug--that is to say, harmless in small quantities. In five seconds the man is dead. At the inquest we find he has been poisoned--cyanide is found in his pocket. And who is this man? Obviously the identical person who witnessed the murder of John Millinborn and whom we have been trying to find ever since that crime."

"Van Heerden won't escape the third time. His presence will be a little more than a coincidence," said the superintendent.

Beale laughed.

"There will be no third time," he said shortly, "van Heerden is not a fool."

"Have you any idea what the secret was that he wanted to get from old Millinborn?" asked the detective.

Beale nodded.

"Yes, I know pretty well," he said, "and in course of time you will know, too."

The detective was glancing over the newspaper account.

"I see the jury returned a verdict of 'Suicide whilst of unsound mind!'" he said. "This case ought to injure van Heerden, anyway."

"That is where you are wrong," said Beale, stopping in his stride, "van Heerden has so manoeuvred the Pressmen that he comes out with an enhanced reputation. You will probably find articles in the weekly papers written and signed by him, giving his views on the indiscriminate sale of poisons. He will move in a glamour of romance, and his consulting-rooms will be thronged by new admirers."

"It's a rum case," said the superintendent, rising, "and if you don't mind my saying so, Mr. Beale, you're one of the rummiest men that figure in it. I can't quite make you out. You are not a policeman and yet we have orders from the Foreign Office to give you every assistance. What's the game?"

"The biggest game in the world," said Beale promptly, "a game which, if it succeeds, will bring misery and suffering to thousands, and will bring great businesses tumbling, and set you and your children and your children's children working for hundreds of years to pay off a new national debt."

"Man alive!" said the other, "are you serious?"

Beale nodded.

"I was never more serious in my life," he said, "that is why I don't want the police to be too inquisitive in regard to this murder of Jackson, whose real name, as I say, is Predeaux. I can tell you this, chief, that you are seeing the development of the most damnable plot that has ever been hatched in the brain of the worst miscreant that history knows. Sit down again. Do you know what happened last year?" he asked.

"Last year?" said the superintendent. "Why, the war ended last year."

"The war ended, Germany was beaten, and had to accept terms humiliating for a proud nation, but fortunately for her Prussia was not proud, she was merely arrogant. Her worst blow was the impoverishing conditions which the Entente Powers imposed. That is to say, they demanded certain concessions of territory and money which, added to ............