“But what was the object of this madness?”

“What was the object? Why, to make people leave him alone and keep them from questioning him or suspecting him. Once he was looked upon as mad, he could remain silent and unobserved. Otherwise, Mme. Essarès would have recognized his voice at the first words he spoke, however cleverly he might have altered his tone. From this time onward, he is mad. He is an irresponsible being. He goes about as he pleases. He is a madman! And his madness is so thoroughly admitted that he leads you, so to speak, by the hand to his former accomplices and causes you to have them arrested, without asking yourself for an instant if this madman is not acting with the clearest possible sense of his own interest. He’s a madman, a poor, harmless madman, one of those unfortunates with whom nobody dreams of interfering. Henceforth, he has only his last two adversaries to fight: Coralie and you. And this is an easy matter for him. I presume that he got hold of a diary kept by your father. At any rate, he knows every day of the one which you keep. From this he learns the whole story of the graves; and he knows that, on the fourteenth of April, Coralie and you are both going on a pilgrimage to those graves. Besides, he plans to make you go there, for his plot is laid. He prepares against the son and the daughter, against the Patrice and Coralie of to-day, the attempt which he once prepared against the father and the mother. The attempt succeeds at the start. It would have succeeded to the end, but for an idea that occurred to our poor Ya-Bon, thanks to which a new adversary, in the person of myself, entered the lists. . . . But I need hardly go on. You know the rest as well as I do; and, like myself, you can judge in all his glory the inhuman villain who, in the space of those twenty-four hours, allowed his accomplice Grégoire to be strangled, buried your Coralie under the sand-heap, killed Ya-Bon, locked me in the lodge, or thought he did, buried you alive in the grave dug by your father and made away with Vacherot, the porter. And now, Captain Belval, do you think that I ought to have prevented him from committing suicide, this pretty gentleman who, in the last resort, was trying to pass himself off as your father?”

“You were right,” said Patrice. “You have been right all through, from start to finish. I see it all now, as a whole and in every detail. Only one point remains: the golden triangle. How did you find out the truth? What was it that brought you to this sand-heap and enabled you to save Coralie from the most awful death?”

“Oh, that part was even simpler,” replied Don Luis, “and the light came almost without my knowing it! I’ll tell it you in a few words. But let us move away first. M. Masseron and his men are becoming a little troublesome.”

The detectives were distributed at the two entrances to Berthou’s Wharf. M. Masseron was giving them his instructions. He was obviously speaking to them of Don Luis and preparing to accost him.

“Let’s get on the barge,” said Don Luis. “I’ve left some important papers there.”

Patrice followed him. Opposite the cabin containing Grégoire’s body was another cabin, reached by the same companion-way. It was furnished with a table and a chair.

“Here, captain,” said Don Luis, taking a letter from the drawer of the table and settling it, “is a letter which I will ask you to . . . but don’t let us waste words. I shall hardly have time to satisfy your curiosity. Our friends are coming nearer. Well, we were saying, the golden triangle . . .”

He listened to what was happening outside with an attention whose real meaning Patrice was soon to understand. And, continuing to give ear, he resumed:

“The golden triangle? There are problems which we solve more or less by accident, without trying. We are guided to a right solution by external events, among which we choose unconsciously, feeling our way in the dark, examining this one, thrusting aside that one and suddenly beholding the object aimed at. . . . Well, this morning, after taking you to the tombs and burying you under the stone, Essarès Bey came back to me. Believing me to be locked into the studio, he had the pretty thought to turn on the gas-meter and then went off to the quay above Berthou’s Wharf. Here he hesitated; and his hesitation provided me with a precious clue. He was certainly then thinking of releasing Coralie. People passed and he went away. Knowing where he was going, I returned to your assistance, told your friends at Essarès’ house and asked them to look after you. Then I came back here. Indeed, the whole course of events obliged me to come back. It was unlikely that the bags of gold were inside the conduit; and, as the Belle Hélène had not taken them off, they must be beyond the garden, outside the conduit and therefore somewhere near here. I explored the barge we are now on, not so much with the object of looking for the bags as with the hope of finding some unexpected piece of information and also, I confess, the four millions in Grégoire’s possession. Well, when I start exploring a place where I fail to find what I want, I always remember that capital story of Edgar Allan Poe’s, The Purloined Letter. Do you recollect? The stolen diplomatic document which was known to be hidden in a certain room. The police investigate every nook and corner of the room and take up all the boards of the floor, without results. But Dupin arrives and almost immediately goes to a card-rack dangling from a little brass knob on the wall and containing a solitary soiled and crumpled letter. This is the document of which he was in search. Well, I instinctively adopted the same process. I looked where no one would dream of looking, in places which do not constitute a hiding-place because it would really be too easy to discover. This gave me the idea of turning the pages of four old directories standing in a row on that shelf. The four millions were there. And I knew all that I wanted to know.”