And, suddenly, Lupin remembered: two years ago, Prasville and Daubrecq the deputy had had a personal encounter on the Place du Palais-Bourbon. The incident made a great stir at the time. No one knew the cause of it. Prasville had sent his seconds to Daubrecq on the same day; but Daubrecq refused to fight.

A little while later, Prasville was appointed secretary-general.

"Very odd, very odd," said Lupin, who remained plunged in thought, while continuing to observe Prasvile's movements.

At seven o'clock Prasville's group of men moved away a few yards, in the direction of the Avenue Henri-Martin. The door of a small garden on the right of the house opened and Daubrecq appeared. The two detectives followed close behind him and, when he took the Rue-Taitbout train, jumped on after him.

Prasville at once walked across the square and rang the bell. The garden-gate was between the house and the porter's lodge. The portress came and opened it. There was a brief conversation, after which Prasville and his companions were admitted.

"A domiciliary visit," said Lupin. "Secret and illegal. By the strict rules of politeness, I ought to be invited. My presence is indispensable."

Without the least hesitation he went up to the house, the door of which had not been closed, and, passing in front of of the portress, who was casting her eyes outside, he asked, in the hurried tones of a person who is late for an appointment:

"Have the gentlemen come?"

"Yes, you will find them in the study."

His plan was quite simple: if any one met him, he would pretend to be a tradesman. But there was no need for this subterfuge. He was able, after crossing an empty hail, to enter a dining-room which also had no one in it, but which, through the panes of a glass partition that separated the dining-room from the study, afforded him a view of Prasville and his five companions.

Prasville opened all the drawers with the aid of false keys. Next, he examined all the papers, while his companions took down the books from the shelves, shook the pages of each separately and felt inside the bindings.

"Of course, it's a paper they're looking for," said Lupin. "Bank-notes, perhaps... "

Prasville exclaimed:

"Whatrot! We shan't find a thing!"

Yet he obviously did not abandon all hope of discovering what he wanted, for he suddenly seized the four bottles in a liqueur-stand, took out the four stoppers and inspected them.

"Hullo!" thought Lupin. "Now he's going for decanter-stoppers! Then it's not a question of a paper? Well, I give it up."

Prasville next lifted and examined different objects; and he asked:

"How often have you been here?"

"Six times last winter," was the reply.

"And you have searched the house thoroughly?"

"Every one of the rooms, for days at a time, while he was visiting his constituency."

"Still... still ... ." And he added, "Has he no servant at present?"

"No, he is looking for one. He has his meals out and the portress keeps the house as best she can. The woman is devoted to us... "

“It is his love diary?”

“Or his lust diary. Call it what you will. The moment the woman told us of it I realized what a tremendous weapon was there if we could but lay our hands on it. I said nothing at the time to indicate my thoughts, for this woman might have given it away. But I brooded over it. Then this assault upon me gave me the chance of letting the Baron think that no precautions need be taken against me. That was all to the good. I would have waited a little longer, but his visit to America forced my hand. He would never have left so compromising a document behind him. Therefore we had to act at once. Burglary at night is impossible. He takes precautions. But there was a chance in the evening if I could only be sure that his attention was engaged. That was where you and your blue saucer came in. But I had to be sure of the position of the book, and I knew I had only a few minutes in which to act, for my time was limited by your knowledge of Chinese pottery. Therefore I gathered the girl up at the last moment. How could I guess what the little packet was that she carried so carefully under her cloak? I thought she had come altogether on my business, but it seems she had some of her own.”

“He guessed I came from you.”

“I feared he would. But you held him in play just long enough for me to get the book, though not long enough for an unobserved escape. Ah, Sir James, I am very glad you have come!”

Our courtly friend had appeared in answer to a previous summons. He listened with the deepest attention to Holmes’s account of what had occurred.

“You have done wonders — wonders!” he cried when he had heard the narrative. “But if these injuries are as terrible as Dr. Watson describes, then surely our purpose of thwarting the marriage is sufficiently gained without the use of this horrible book.”

Holmes shook his head.

“Women of the De Merville type do not act like that. She would love him the more as a disfigured martyr. No, no. It is his moral side, not his physical, which we have to destroy. That book will bring her back to earth — and I know nothing else that could. It is in his own writing. She cannot get past it.”

Sir James carried away both it and the precious saucer. As I was myself overdue, I went down with him into the street. A brougham was waiting for him. He sprang in, gave a hurried order to the cockaded coachman, and drove swiftly away. He flung his overcoat half out of the window to cover the armorial bearings upon the panel, but I had seen them in the glare of our fanlight none the less. I gasped with surprise. Then I turned back and ascended the stair to Holmes’s room.

“I have found out who our client is,” I cried, bursting with my great news. “Why, Holmes, it is —”

“It is a loyal friend and a chivalrous gentleman,” said Holmes, holding up a restraining hand. “Let that now and forever be enough for us.”

I do not know how the incriminating book was used. Sir James may have managed it. Or it is more probable that so delicate a task was entrusted to the young lady’s father. The effect, at any rate, was all that could be desired.