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 the portress, who was 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... "

“Well, well, we have made a beginning. I should not expect any fresh developments until next Tuesday. In the meantime we can only keep in touch with friend Bennett and enjoy the amenities of this charming town.”

In the morning Mr. Bennett slipped round to bring us the latest report. As Holmes had imagined, times had not been easy with him. Without exactly accusing him of being responsible for our presence, the professor had been very rough and rude in his speech, and evidently felt some strong grievance. This morning he was quite himself again, however, and had delivered his usual brilliant lecture to a crowded class. “Apart from his queer fits,” said Bennett, “he has actually more energy and vitality than I can ever remember, nor was his brain ever clearer. But it’s not he — it’s never the man whom we have known.”

“I don’t think you have anything to fear now for a week at least,” Holmes answered. “I am a busy man, and Dr. Watson has his patients to attend to. Let us agree that we meet here at this hour next Tuesday, and I shall be surprised if before we leave you again we are not able to explain, even if we cannot perhaps put an end to, your troubles. Meanwhile, keep us posted in what occurs.”

I saw nothing of my friend for the next few days, but on the following Monday evening I had a short note asking me to meet him next day at the train. From what he told me as we travelled up to Camford all was well, the peace of the professor’s house had been unruffled, and his own conduct perfectly normal. This also was the report which was given us by Mr. Bennett himself when he called upon us that evening at our old quarters in the Chequers. “He heard from his London correspondent to-day. There was a letter and there was a small packet, each with the cross under the stamp which warned me not to touch them. There has been nothing else.”

“That may prove quite enough,” said Holmes grimly. “Now, Mr. Bennett, we shall, I think, come to some conclusion tonight. If my deductions are correct we should have an opportunity of bringing matters to a head. In order to do so it is necessary to hold the professor under observation. I would suggest, therefore, that you remain awake and on the lookout. Should you hear him pass your door, do not interrupt him, but follow him as discreetly as you can. Dr. Watson and I will not be far off. By the way, where is the key of that little box of which you spoke?”

“Upon his watch-chain.”

“I fancy our researches must lie in that direction. At the worst the lock should not be very formidable. Have you any other able-bodied man on the premises?”

“There is the coachman, Macphail.”

“Where does he sleep?”

“Over the stables.”

“We might possibly want him. Well, we can do no more until we see how things develop, Good-bye — but I expect that we shall see you before morning.”

It was nearly midnight before we took our station among some bushes immediately opposite the hall door of the professor. It was a fine night, but chilly, and we were glad of our warm overcoats. There was a breeze, and clouds were scudding across the sky, obscuring from time to time the half-moon. It would have been a dismal vigil were it not for the expectation and excitement which carried us along, and the assurance of my comrade that we had probably reached the end of the strange sequence of events which had engaged our attention.