"If he is there, he will escape from the Needle by the other side, the side overlooking the sea."

"In that case, he will at once be arrested by the other half of my men."

"Yes, but if, as I presume, you choose a moment when the sea is at low ebb, leaving the base of the Needle uncovered, the chase will be public, because it will take place before all the men and women fishing for mussels, shrimps and sh.e.l.l-fish who swarm on the rocks round about."

"That is why I just mean to select the time when the sea is full."

"In that case, he will make off in a boat."

"Ah, but I shall have a dozen fishing-smacks, each of which will be commanded by one of my men, and we shall collar him-"

"If he doesn't slip through your dozen smacks, like a fish through the meshes."

"All right, then I'll sink him."

"The devil you will! Shall you have guns?"

"Why, of course! There's a torpedo-boat at the Havre at this moment. A telegram from me will bring her to the Needle at the appointed hour."

"How proud Lupin will be! A torpedo-boat! Well, M. Ganimard, I see that you have provided for everything. We have only to go ahead. When do we deliver the a.s.sault?"

"To-morrow."

"At night?"

"No, by daylight, at the flood-tide, as the clock strikes ten in the morning."

"Capital."

Under his show of gaiety, Beautrelet concealed a real anguish of mind. He did not sleep until the morning, but lay pondering over the most impracticable schemes, one after the other.

Ganimard had left him in order to go to Yport, six or seven miles from Etretat, where, for prudence's sake, he had told his men to meet him, and where he chartered twelve fishing smacks, with the ostensible object of taking soundings along the coast.

At a quarter to ten, escorted by a body of twelve stalwart men, he met Isidore at the foot of the road that goes up the cliff.

At ten o'clock exactly, they reached the skirt of wall. It was the decisive moment.

At ten o'clock exactly.

"Why, what's the matter with you, Beautrelet?" jeered Ganimard. "You're quite green in the face!"

"It's as well you can't see yourself, Ganimard," the boy retorted. "One would think your last hour had come!"

They both had to sit down and Ganimard swallowed a few mouthfuls of rum.

"It's not funk," he said, "but, by Jove, this is an exciting business! Each time that I'm on the point of catching him, it takes me like that in the pit of the stomach. A dram of rum?"

"No."

"And if you drop behind?"

"That will mean that I'm dead."

"B-r-r-r-r! However, we'll see. And now, open, sesame! No danger of our being observed, I suppose?"

"No. The Needle is not so high as the cliff, and, besides, there's a bend in the ground where we are."

Beautrelet went to the wall and pressed upon the brick. The bolt was released and the underground pa.s.sage came in sight.

By the gleam of the lanterns which they lit, they saw that it was cut in the shape of a vault and that both the vaulting and the floor itself were entirely covered with bricks.

They walked for a few seconds and, suddenly, a staircase appeared. Beautrelet counted forty-five brick steps, which the slow action of many footsteps had worn away in the middle.

"Blow!" said Ganimard, holding his head and stopping suddenly, as though he had knocked against something.

"What is it?"

"A door."

"Bother!" muttered Beautrelet, looking at it. "And not an easy one to break down either. It's just a solid block of iron."

"We are done," said Ganimard. "There's not even a lock to it."

"Exactly. That's what gives me hope."

"Why?"

"A door is made to open; and, as this one has no lock, that means that there is a secret way of opening it."

"And, as we don't know the secret-"

"I shall know it in a minute."

"How?"

"By means of the doc.u.ment. The fourth line has no other object but to solve each difficulty as and when it crops up. And the solution is comparatively easy, because it's not written with a view to throwing searchers off the scent, but to a.s.sisting them."

"Comparatively easy! I don't agree with you," cried Ganimard, who had unfolded the doc.u.ment. "The number 44 and a triangle with a dot in it: that doesn't tell us much!"

"Yes, yes, it does! Look at the door. You see it's strengthened, at each corner, with a triangular slab of iron; and the slabs are fixed with big nails. Take the left-hand bottom slab and work the nail in the corner: I'll lay ten to one we've hit the mark."

"You've lost your bet," said Ganimard, after trying.

"Then the figure 44 must mean-"

In a low voice, reflecting as he spoke, Beautrelet continued:

"Let me see-Ganimard and I are both standing on the bottom step of the staircase-there are 45. Why 45, when the figure in the doc.u.ment is 44? A coincidence? No. In all this business, there is no such thing as a coincidence, at least not an involuntary one. Ganimard, be so good as to move one step higher up. That's it, don't leave this forty-fourth step. And now I will work the iron nail. And the trick's done, or I'll eat my boots!"