One hope remained, the summoning of the household; and Father Brown ran back into the house. He found, however, that all the under servants had been given a holiday ashore by the autocrat Paul, and that only the sombre Mrs. Anthony moved uneasily about the long rooms. But the moment she turned a ghastly face upon him, he resolved one of the riddles of the house of mirrors. The heavy brown eyes of Antonelli were the heavy brown eyes of Mrs. Anthony; and in a flash he saw half the story.

"Your son is outside," he said without wasting words; "either he or the prince will be killed. Where is Mr. Paul?"

"He is at the landing-stage," said the woman faintly. "He is—he is—signalling for help."

"Mrs. Anthony," said Father Brown seriously, "there is no time for nonsense. My friend has his boat down the river fishing. Your son's boat is guarded by your son's men. There is only this one canoe; what is Mr. Paul doing with it?"

"Santa Maria! I do not know," she said; and swooned all her length on the matted floor.

Father Brown lifted her to a sofa, flung a pot of water over her, shouted for help, and then rushed down to the landing-stage of the little island. But the canoe was already in mid-stream, and old Paul was pulling and pushing it up the river with an energy incredible at his years.

"I will save my master," he cried, his eyes blazing maniacally. "I will save him yet!"

Father Brown could do nothing but gaze after the boat as it struggled up-stream and pray that the old man might waken the little town in time.

"A duel is bad enough," he muttered, rubbing up his rough dust-coloured hair, "but there's something wrong about this duel, even as a duel. I feel it in my bones. But what can it be?"

As he stood staring at the water, a wavering mirror of sunset, he heard from the other end of the island garden a small but unmistakable sound—the cold concussion of steel. He turned his head.

Away on the farthest cape or headland of the long islet, on a strip of turf beyond the last rank of roses, the duellists had already crossed swords. Evening above them was a dome of virgin gold, and, distant as they were, every detail was picked out. They had cast off their coats, but the yellow waistcoat and white hair of Saradine, the red waistcoat and white trousers of Antonelli, glittered in the level light like the colours of the dancing clockwork dolls. The two swords sparkled from point to pommel like two diamond pins. There was something frightful in the two figures appearing so little and so gay. They looked like two butterflies trying to pin each other to a cork.

Father Brown ran as hard as he could, his little legs going like a wheel. But when he came to the field of combat he found he was born too late and too early—too late to stop the strife, under the shadow of the grim Sicilians leaning on their oars, and too early to anticipate any disastrous issue of it. For the two men were singularly well matched, the prince using his skill with a sort of cynical confidence, the Sicilian using his with a murderous care. Few finer fencing matches can ever have been seen in crowded amphitheatres than that which tinkled and sparkled on that forgotten island in the reedy river. The dizzy fight was balanced so long that hope began to revive in the protesting priest; by all common probability Paul must soon come back with the police. It would be some comfort even if Flambeau came back from his fishing, for Flambeau, physically speaking, was worth four other men. But there was no sign of Flambeau, and, what was much queerer, no sign of Paul or the police. No other raft or stick was left to float on; in that lost island in that vast nameless pool, they were cut off as on a rock in the Pacific.

Almost as he had the thought the ringing of the rapiers quickened to a rattle, the prince's arms flew up, and the point shot out behind between his shoulder-blades. He went over with a great whirling movement, almost like one throwing the half of a boy's cart-wheel. The sword flew from his hand like a shooting star, and dived into the distant river. And he himself sank with so earth-shaking a subsidence that he broke a big rose-tree with his body and shook up into the sky a cloud of red earth—like the smoke of some heathen sacrifice. The Sicilian had made blood-offering to the ghost of his father.

The priest was instantly on his knees by the corpse; but only to make too sure that it was a corpse. As he was still trying some last hopeless tests he heard for the first time voices from farther up the river, and saw a police boat shoot up to the landing-stage, with constables and other important people, including the excited Paul. The little priest rose with a distinctly dubious grimace.

"Now, why on earth," he muttered, "why on earth couldn't he have come before?"

Some seven minutes later the island was occupied by an invasion of townsfolk and police, and the latter had put their hands on the victorious duellist, ritually reminding him that anything he said might be used against him.

"I shall not say anything," said the monomaniac, with a wonderful and peaceful face. "I shall never say anything more. I am very happy, and I only want to be hanged."

Then he shut his mouth as they led him away, and it is the strange but certain truth that he never opened it again in this world, except to say "Guilty" at his trial.

Father Brown had stared at the suddenly crowded garden, the arrest of the man of blood, the carrying away of the corpse after its examination by the doctor, rather as one watches the break-up of some ugly dream; he was motionless, like a man in a nightmare. He gave his name and address as a witness, but declined their offer of a boat to the shore, and remained alone in the island garden, gazing at the broken rose bush and the whole green theatre of that swift and inexplicable tragedy. The light died along the river; mist rose in the marshy banks; a few belated birds flitted fitfully across.

Stuck stubbornly in his sub-consciousness (which was an unusually lively one) was an unspeakable certainty that there was something still unexplained. This sense that had clung to him all day could not be fully explained by his fancy about "looking-glass land." Somehow he had not seen the real story, but some game or masque. And yet people do not get hanged or run through the body for the sake of a charade.

As he sat on the steps of the landing-stage ruminating he grew conscious of the tall, dark streak of a sail coming silently down the shining river, and sprang to his feet with such a backrush of feeling that he almost wept.

"Flambeau!" he cried, and shook his friend by both hands again and again, much to the astonishment of that sportsman, as he came on shore with his fishing tackle. "Flambeau," he said, "so you're not killed?"

"Killed!" repeated the angler in great astonishment. "And why should I be killed?"

"Oh, because nearly everybody else is," said his companion rather wildly. "Saradine got murdered, and Antonelli wants to be hanged, and his mother's fainted, and I, for one, don't know whether I'm in this world or the next. But, thank God, you're in the same one." And he took the bewildered Flambeau's arm.

As they turned from the landing-stage they came under the eaves of the low bamboo house, and looked in through one of the windows, as they had done on their first arrival. They beheld a lamp-lit interior well calculated to arrest their eyes. The table in the long dining-room had been laid for dinner when Saradine's destroyer had fallen like a stormbolt on the island. And the dinner was now in placid progress, for Mrs. Anthony sat somewhat sullenly at the foot of the table, while at the head of it was Mr. Paul, the major domo, eating and drinking of the best, his bleared, bluish eyes standing queerly out of his face, his gaunt countenance inscrutable, but by no means devoid of satisfaction.