The Etretat Needle was hollow!
 
Was it a natural phenomenon, an excavation produced by internal cataclysms or by the imperceptible action of the rushing sea and the soaking rain? Or was it a superhuman work executed by human beings, Gauls, Celts, prehistoric men?
 
These, no doubt, were insoluble questions; and what did it matter? The essence of the thing was contained in this fact: The Needle was hollow. At forty or fifty yards from that imposing arch which is called the Porte d'Aval and which shoots out from the top of the cliff, like the colossal branch of a tree, to take root in the submerged rocks, stands an immense limestone cone; and this cone is no more than the shell of a pointed cap poised upon the empty waters!
 
A prodigious revelation! After Lupin, here was Beautrelet discovering the key to the great riddle that had loomed over more than twenty centuries! A key of supreme importance to whoever possessed it in the days of old, in those distant times when hordes of barbarians rode through and overran the old world! A magic key that opens the cyclopean cavern to whole tribes fleeing before the enemy! A mysterious key that guards the door of the most inviolable shelter! An enchanted key that gives power and ensures preponderance!
 
Because he knows this key, Caesar is able to subdue Gaul. Because they know it, the Normans force their sway upon the country and, from there, later, backed by that support, conquer the neighboring island, conquer Sicily, conquer the East, conquer the new world!
 
Masters of the secret, the Kings of England lord it over France, humble her, dismember her, have themselves crowned at Paris. They lose the secret; and the rout begins.
 
Masters of the secret, the Kings of France push back and overstep the narrow limits of their dominion, gradually founding a great nation and radiating with glory and power. They forget it or know not how to use it; and death, exile, ruin follow.
 
An invisible kingdom, in mid-water and at ten fathoms from land! An unknown fortress, taller than the towers of Notre Dame and built upon a granite foundation larger than a public square! What strength and what security! From Paris to the sea, by the Seine. There, the Havre, the new town, the necessary town. And, sixteen miles thence, the Hollow Needle, the impregnable sanctuary!
 
It is a sanctuary and also a stupendous hiding-place. All the treasures of the kings, increasing from century to century, all the gold of France, all that they extort from the people, all that they snatch from the clergy, all the booty gathered on the battle-fields of Europe lie heaped up in the royal cave. Old Merovingian gold sous, glittering crown-pieces, doubloons, ducats, florins, guineas; and the precious stones and the diamonds; and all the jewels and all the ornaments: everything is there. Who could discover it? Who could ever learn the impenetrable secret of the Needle? Nobody.
 
And Lupin becomes that sort of really disproportionate being whom we know, that miracle incapable of explanation so long as the truth remains in the shadow. Infinite though the resources of his genius be, they cannot suffice for the mad struggle which he maintains against society. He needs other, more material resources. He needs a sure place of retreat, he needs the certainty of impunity, the peace that allows of the execution of his plans.
 
Without the Hollow Needle, Lupin is incomprehensible, a myth, a character in a novel, having no connection with reality.
 
Master of the secret—and of such a secret!—he becomes simply a man like another, but gifted with the power of wielding in a superior manner the extraordinary weapon with which destiny has endowed him.
 
So the Needle was hollow.
 
It remained to discover how one obtained access to it.
 
From the sea, obviously. There must be, on the side of the offing, some fissure where boats could land at certain hours of the tide.
 
But on the side of the land?
 
Beautrelet lay until ten o'clock at night hanging over the precipice, with his eyes riveted on the shadowy mass formed by the pyramid, thinking and pondering with all the concentrated effort of his mind.
 
Then he went down to Etretat, selected the cheapest hotel, dined, went up to his room and unfolded the document.
 
It was the merest child's play to him now to establish its exact meaning. He at once saw that the three vowels of the word Etretat occurred in the first line, in their proper order and at the necessary intervals. This first line now read as follows:
 
  e . a . a .. etretat . a ..
 
What words could come before Etretat? Words, no doubt, that referred to the position of the Needle with regard to the town. Now the Needle stood on the left, on the west—He ransacked his memory and, recollecting that westerly winds are called vents d'aval on the coast and that the nearest porte was known as the Porte d'Aval, he wrote down:
 
  "En aval d'Etretat . a .."
 
The second line was that containing the word Demoiselles and, at once seeing, in front of that word, the series of all the vowels that form part of the words la chambre des, he noted the two phrases:
 
  "En aval d'Etretat. La Chambre des Demoiselles."
 
The third line gave him more trouble; and it was not until some groping that, remembering the position, near the Chambre des Demoiselles, of the Fort de Frefosse, he ended by almost completely reconstructing the document:
 
  "En aval d'Etretat. La Chambre des Demoiselles. Sous le Fort de
  Frefosse. L'Aiguille creuse."
 
These were the four great formulas, the essential and general formulas which you had to know. By means of them, you turned en aval, that is to say, below or west of Etretat, entered the Chambre des Demoiselles, in all probability passed under Fort Frefosse and thus arrived at the Needle.
 
How? By means of the indications and measurements that constituted the fourth line:
 
[Illustration: drawing of an outline of paper with writing and drawing on it—numbers, dots, some letters, signs and symbols...]
 
These were evidently the more special formulas to enable you to find the outlet through which you made your way and the road that led to the Needle.
 
Beautrelet at once presumed—and his surmise was no more than the logical consequence of the document—that, if there really was a direct communication between the land and the obelisk of the Needle, the underground passage must start from the Chambre des Demoiselles, pass under Fort Frefosse, descend perpendicularly the three hundred feet of cliff and, by means of a tunnel contrived under the rocks of the sea, end at the Hollow Needle.
 
Which was the entrance to the underground passage? Did not the two letters D and F, so plainly cut, point to it and admit to it, with the aid, perhaps, of some ingenious piece of mechanism?
 
The whole of the next morning, Isidore strolled about Etretat and chatted with everybody he met, in order to try and pick up useful information. At last, in the afternoon, he went up the cliff. Disguised as a sailor, he had made himself still younger and, in a pair of trousers too short for him and a fishing jersey, he looked a mere scape-grace of twelve or thirteen.
 
As soon as he entered the cave, he knelt down before the letters. Here a disappointment awaited him. It was no use his striking them, pushing them, manipulating them in every way: they refused to move. And it was not long, in fact, before he became aware that they were really unable to move and that, therefore, they controlled no mechanism.
 
And yet—and yet they must mean something! Inquiries which he had made in the village went to show that no one had ever been able to explain their existence and that the Abbe Cochet, in his valuable little book on Etretat,[8] had also tried in vain to solve this little puzzle. But Isidore knew what the learned Norman archaeologist did not know, namely, that the same two letters figured in the document, on the line containing the indications. Was it a chance coincidence: Impossible. Well, then—?
 
[8]Les Origines d'Etretat. The Abbe Cochet seems to conclude, in the end, that the two letters are the initials of a passer-by. The revelations now made prove the fallacy of the theory.
 
An idea suddenly occurred to him, an idea so reasonable, so simple that he did not doubt its correctness for a second. Were not that D and that F the initials of the two most important words in the document, the words that represented—together with the Needle—the essential stations on the road to be followed: the Chambre des Demoiselles and Fort Frefosse: D for Demoiselles, F for Frefosse: the connection was too remarkable to be a mere accidental fact.
 
In that case, the problem stood thus: the two letters D F represent the relation that exists between the Chambre des Demoiselles and Fort Frefosse, the single letter D, which begins the line, represents the Demoiselles, that is to say, the cave in which you have to begin by taking up your position, and the single letter F, placed in the middle of the line, represents Frefosse, that is to say, the probable entrance to the underground passage.
 
Between these various signs, are two more: first, a sort of irregular rectangle, marked with a stripe in the left bottom corner, and, next, the figure 19, signs which obviously indicate to those inside the cave the means of penetrating beneath the fort.
 
The shape of this rectangle puzzled Isidore. Was there around him, on the walls of the cave, or at any rate within reach of his eyes, an inscription, anything whatever, affecting a rectangular shape?
 
He looked for a long time and was on the point of abandoning that particular scent when his eyes fell upon the little opening, pierced in the rock, that acted as a window to the chamber.
 
Now the edges of this opening just formed a rectangle: corrugated, uneven, clumsy, but still a rectangle; and Beautrelet at once saw that, by placing his two feet on the D and the F carved in the stone floor—and this explained the stroke that surmounted the two letters in the document—he found himself at the exact height of the window!
 
He took up his position in this place and gazed out. The window looking landward, as we know, he saw, first, the path that connected the cave with the land, a path hung between two precipices; and, next, he caught sight of the foot of the hillock on which the fort stood. To try and see the fort, Beautrelet leaned over to the left and it was then that he understood the meaning of the curved stripe, the comma that marked the left bottom corner in the document: at the bottom on the left-hand side of the window, a piece of flint projected and the end of it was curved like a claw. It suggested a regular shooter's mark. And, when a man applied his eye to this mark, he saw cut out, on the slope of the mound facing him, a restricted surface of land occupied almost entirely by an old brick wall, a remnant of the original Fort Frefosse or of the old Roman oppidum built on this spot.
 
Beautrelet ran to this piece of wall, which was, perhaps, ten yards long. It was covered with grass and plants. There was no indication of any kind visible. And yet that figure 19?
 
He returned to the cave, took from his pocket a ball of string and a tape-measure, tied the string to the flint corner, fastened a pebble at the nineteenth metre and flung it toward the land side. The pebble at most reached the end of the path.
 
"Idiot that I am!" thought Beautrelet. "Who reckoned by metres in those days? The figure 19 means 19 fathoms[9] or nothing!"
 
[9] The toise, or fathom, measured 1.949 metres.—Translator's Note.
 
Having made the calculation, he ran out the twine, made a knot and felt about on the piece of wall for the exact and necessarily one point at which the knot, formed at 37 metres from the window of the Demoiselles, should touch the Frefosse wall. In a few moments, the point of contact was established. With his free hand, he moved aside the leaves of mullein that had grown in the interstices. A cry escaped him. The knot, which he held pressed down with his fore-finger, was in the centre of a little cross carved in relief on a brick. And the sign that followed on the figure 19 in the document was a cross!
 
It needed all his will-power to control the excitement with which he was overcome. Hurriedly, with convulsive fingers, he clutched the cross and, pressing upon it, turned it as he would have turned the spokes of a wheel. The brick heaved. He redoubled his effort; it moved no further. Then, without turning, he pressed harder. He at once felt the brick give way. And, suddenly, there was the click of a bolt that is released, the sound of a lock opening and, on the right of the brick, to the width of about a yard, the wall swung round on a pivot and revealed the orifice of an underground passage.
 
Like a madman, Beautrelet seized the iron door in which the bricks were sealed, pulled it back, violently and closed it. Astonishment, delight, the fear of being surprised convulsed his face so as to render it unrecognizable. He beheld the awful vision of all that had happened there, in front of that door, during twenty centuries; of all those people, initiated into the great secret, who had penetrated through that issue: Celts, Gauls, Romans, Normans, Englishmen, Frenchmen, barons, dukes, kings—and, after all of them, Arsene Lupin—and, after Lupin, himself, Beautrelet. He felt that his brain was slipping away from him. His eyelids fluttered. He fell fainting and rolled to the bottom of the slope, to the very edge of the precipice.
 
His task was done, at least the task which he was able to accomplish alone, with his unaided resources.
 
That evening, he wrote a long letter to the chief of the detective service, giving a faithful account of the results of his investigations and revealing the secret of the Hollow Needle. He asked for assistance to complete his work and gave his address.
 
While waiting for the reply, he spent two consecutive nights in the Chambre des Demoiselles. He spent them overcome with fear, his nerves shaken with a terror which was increased by the sounds of the night. At every moment, he thought he saw shadows approach in his direction. People knew of his presence in the cave—they were coming—they were murdering him!
 
His eyes, however, staring madly before them, sustained by all the power of his will, clung to the piece of wall.
 
On the first night, nothing stirred; but, on the second, by the light of the stars and a slender crescent-moon, he saw the door open and figures emerge from the darkness: he counted two, three, four, five of them.
 
It seemed to him that those five men were carrying fairly large loads. He followed them for a little way. They cut straight across the fields to the Havre road; and he heard the sound of a motor car driving away.
 
He retraced his steps, skirting a big farm. But, at the turn of the road that ran beside it, he had only just time to scramble up a slope and hide behind some trees. More men passed—four, five men—all carrying packages. And, two minutes later, another motor snorted.
 
This time, he had not the strength to return to his post; and he went back to bed.
 
When he woke and had finished dressing, the hotel waiter brought him a letter. He opened it. It contained Ganimard's card.
 
"At last!" cried Beautrelet, who, after so hard a campaign, was really feeling the need of a comrade-in-arms.
 
He ran downstairs with outstretched hands. Ganimard took them, looked at him for a moment and said:
 
"You're a fine fellow, my lad!"
 
"Pooh!" he said. "Luck has served me."
 
"There's no such thing as luck with 'him,'" declared the inspector, who always spoke of Lupin in a solemn tone and without mentioning his name.
 
He sat down:
 
"So we've got him!"
 
"Just as we've had him twenty times over," said Beautrelet, laughing.
 
"Yes, but to-day—"
 
"To-day, of course, the case is different. We know his retreat,............