"What proof? The evidence of the grand-duke's wife, the confidences which she made to the servant after her husband's death."

"Yes ... yes ..." stammered Lupin. "We have the evidence of the grand-duke himself."

"Better still," said Steinweg.

"What?"

"A document, a document written in his own hand, signed by him and containing ..."

"Containing what?"

"A list of the secret papers confided to his charge."

"Tell me, in two words... ."

"In two words? That can't be done. The document is a very long one, scattered all over with annotations and remarks which are sometimes impossible to understand. Let me mention just two titles which obviously refer to two bundles of secret papers: _Original letters of the Crown Prince to Bismarck_ is one. The dates show that these letters were written during the three months of the reign of Frederick III. To picture what the letters may contain, you have only to think of the Emperor Frederick's illness, his quarrels with his son ..."

"Yes, yes, I know... . And the other title?"

"_Photographs of the letters of Frederick III., and the Empress Victoria to the Queen of England._"

"Do you mean to say that that's there?" asked Lupin, in a choking voice.

"Listen to the grand-duke's notes: _Text of the treaty with Great Britain and France._ And these rather obscure words: 'Alsace-Lorraine.

... Colonies... . Limitation of naval armaments... ."

"It says that?" blurted Lupin. "And you call that obscure? ... Why, the words are dazzling with light! ... Oh, can it be possible? ...

And what next, what next?"

As he spoke there was a noise at the door. Some one was knocking.

"You can't come in," said Lupin. "I am busy... . Go on, Steinweg."

"But ..." said the old man, in a great state of alarm.

The door was shaken violently and Lupin recognized Weber's voice. He shouted:

"A little patience, Weber. I shall have done in five minutes."

He gripped the old man's arm and, in a tone of command:

"Be easy and go on with your story. So, according to you, the expedition of the grand duke and his servant to Veldenz Castle had no other object than to hide those papers?"

"There can be no question about that."

"Very well. But the grand-duke may have taken them away since."

"No, he did not leave Dresden until his death."

"But the grand-duke's enemies, the men who had everything to gain by recovering them and destroying them: can't they have tried to find out where the papers were?"

"They have tried."

"How do you know?"

"You can understand that I did not remain inactive and that my first care, after receiving those revelations, was to go to Veldenz and make inquiries for myself in the neighboring villages. Well, I learnt that, on two separate occasions, the castle was invaded by a dozen men, who came from Berlin furnished with credentials to the regents."

"Well?"

"Well, they found nothing, for, since that time, the castle has been found closed to the public."

"But what prevents anybody from getting in?"

"A garrison of fifty soldiers, who keep watch day and night."

"Soldiers of the grand-duchy?"

"No, soldiers drafted from the Emperor's own body-guard."

The din in the passage increased:

"Open the door!" a voice cried. "I order you to open the door!"

"I can't. Weber, old chap; the lock has stuck. If you take my advice, you had better cut the door all round the lock."

"Open the door!"

"And what about the fate of Europe, which we are discussing?"

He turned to the old man:

"So you were not able to enter the castle?"

"No."

"But you are persuaded that the papers in question are hidden there?"

"Look here, haven't I given you proofs enough? Aren't you convinced?"

"Yes, yes," muttered Lupin, "that's where they are hidden ... there's no doubt about it ... that's where they are hidden... ."

He seemed to see the castle. He seemed to conjure up the mysterious hiding-place. And the vision of an inexhaustible treasure, the dream of chests filled with riches and precious stones could not have excited him more than the idea of those few scraps of paper watched over by the Kaiser's guards. What a wonderful conquest to embark upon! And how worthy of his powers! And what a proof of perspicacity and intuition he had once more given by throwing himself at a venture upon that unknown track!

Outside, the men were "working" at the lock.

Lupin asked of old Steinweg:

"What did the grand-duke die of?"