Holmes sat for some time in silent thought. He had lit the oldest and foulest of his pipes.

“I am not clear yet what you want me to do in this matter, Mr. Mason,” he said at last. “Can’t you make it more definite?”

“Perhaps this will make it more definite, Mr. Holmes,” said our visitor.

He took a paper from his pocket, and, unwrapping it carefully, he exposed a charred fragment of bone.

Holmes examined it with interest.

“Where did you get it?”

“There is a central heating furnace in the cellar under Lady Beatrice’s room. It‘s been off for some time, but Sir Robert complained of cold and had it on again.

Harvey runs it — he’s one of my lads. This very morning he came to me with this which he found raking out the cinders. He didn’t like the look of it.”

“Nor do I,” said Holmes. “What do you make of it, Watson?”

It was burned to a black cinder, but there could be no question as to its anatomical significance.

“It’s the upper condyle of a human femur,” said I.

“Exactly!” Holmes had become very serious. “When does this lad tend to the furnace?”

“He makes it up every evening and then leaves it.”

“Then anyone could visit it during the night?”

“Yes, sir.”

“Can you enter it from outside?”

“There is is one door from outside. There is another which leads up by a stair to the passage in which Lady Beatrice’s room is situated.”

“These are deep waters, Mr. Mason; deep and rather dirty. You say that Sir Robert was not at home last night?”

“No, sir.”

“Then, whoever was burning bones, it was not he.”

“That’s true, sir.”

“What is the name of that inn you spoke of?”

“The Green Dragon.”

“Is there good fishing in that part of Berkshire?” The honest trainer showed very clearly upon his face that he was convinced that yet another lunatic had come into his harassed life.

“Well, sir, I’ve heard there are trout in the mill-stream and pike in the Hall lake.”

“That’s good enough. Watson and I are famous fishermen — are we not, Watson? You may address us in future at the Green Dragon. We should reach it to-night. I need not say that we don’t want to see you, Mr. Mason, but a note will reach us, and no doubt I could find you if I want you. When we have gone a little farther into the matter I will let you have a considered opinion.”

Thus it was that on a bright May evening Holmes and I found ourselves alone in a first-class carriage and bound for the little “halt-on-demand” station of Shoscombe. The rack above us was covered with a formidable litter of rods, reels, and baskets. On reaching our destination a short drive took us to an old-fashioned tavern, where a sporting host, Josiah Barnes, entered eagerly into our plans for the extirpation of the fish of the neighbourhood.

"The house in the Square Lamartine is occupied by Prasville's men."

"Don't worry, Sebastiani. I shall get in. If they don't open the door, there's always the window. And, if the window won't open, I shall arrange with one of Prasville's men. It's a question of money, that's all. And, thank goodness, I shan't be short of that, henceforth! Good-night, Daubrecq."

He went out, accompanied by Sebastiani, and the heavy door closed after them.

Lupin at once effected his retreat, in accordance with a plan which he had worked out during this scene.

The plan was sunple enough: to scramble, by means of his rope, to the bottom of the cliff, take his friends with him, jump into the motor-car and attack d'Albufex and Sebastiani on the deserted road that leads to Aumale Station. There could be no doubt about the issue of the contest. With d'Albufex and Sebastiani prisoners; it would be an easy matter to make one of them speak. D'Albufex had shown him how to set about it; and Clarisse Mergy would be inflexible where it was a question of saving her son.

He took the rope with which he had provided himself and groped about to find a jagged piece of rock round which to pass it, so as to leave two equal lengths hanging, by which he could let himself down. But, when he found what he wanted, instead of acting swiftly - for the business was urgent - he stood motionless, thinking. His scheme failed to satisfy him at the last moment.

"It's absurd, what I'm proposing," he said to himself. "Absurd and illogical. How can I tell that d'Albufex and Sebastiani will not escape me? How can I even tell that, once they are in my power, they will speak? No, I shall stay. There are better things to try... much better things. It's not those two I must be at, but Daubrecq. He's done for; he has not a kick left in him. If he has told the marquis his secret, there is no reason why he shouldn't tell it to Clarisse and me, when we employ the same methods. That's settled! We'll kidnap the Daubrecq bird." And he continued, "Besides, what do I risk? If the scheme miscarries, Clarisse and I will rush off to Paris and, together with Prasville, organize a careful watch in the Square Lamartine to prevent d'Albufex from benefiting by Daubrecq's revelations. The great thing is for Prasville to be warned of the danger. He shall be."

The church-clock in a neighbouring village struck twelve. That gave Lupin six or seven hours to put his new plan into execution. He set to work forthwith.

When moving away from the embrasure which had the window at the bottom of it, he had come upon a clump of small shrubs in one of the hollows of the cliff. He cut away a dozen of these, with his knife, and whittled them all down to the same size. Then he cut off two equal lengths from his rope. These were the uprights of the ladder. He fastened the twelve little sticks between the uprights and thus contrived a rope-ladder about six yards long.

When he returned to this post, there was only one of the three sons beside Daubrecq's bed in the torture-chamber. He was smoking his pipe by the lamp. Daubrecq was asleep.