“Alone. There is no danger. Besides, one of us must remain here, and one person can more easily keep out of sight than two. My fear is that the boat may be used again. The patrol is not to prevent the boat being used. He is not to show himself; he is merely to observe. You understand?”

“Then you insist on my going?”

“No, I entreat you to go.”

And without more words she went. It was her figure, and not the figure of Rosie, that Mr. Jetsam had seen in the gardens when he peeped out of the window of Mrs. Ilam’s bedroom.

Carpentaria, now alone, recommenced from a fresh spot his vigil over the closed house. He argued with himself with much ingenuity as to what point the persons who wished to enter it would choose for their appearance, but he could decide nothing. They might, he thought, come by the avenue, or round by the back from the other side of the buildings of the Central Way, or even through the gardens. He was growing impatient of a delay apparently interminable, and then his glance happened to wander upwards to the roof of the house. He could not see the roof itself, because he was now too near the wall, but it appeared to him that he detected a phenomenon above the roof which was somewhat unusual. He walked carefully away from the house until the expanse of roof became visible; and, indeed, he had not been mistaken. There was a radiance there. The small square pane of the attic, flat with the surface of the roof itself, was illuminated, and sent up a faint shaft of light into the sky.

Instantly he saw his own shortcomings as a counter-schemer against schemers. He had assumed that the schemers were not already in the house, whereas he had had no grounds for such an assumption. The schemers were most obviously in the house, and they had most obviously been there for a considerable time, since no one could have recently entered it without his knowledge. He was angry with the schemers, and he was more angry with himself, and one of those wild ideas seized him—one of those ideas which could only occur to a Carpentaria. He would catch these schemers himself, by his own devices, and he would do it leisurely, dramatically, and effectively. He would make such a capture as never had been made before. He did not know precisely who the schemers were, nor their numbers, nor their nefarious occupations in the house; and he did not care. When once he was in the toils of a grand romantic idea he cared for nothing except the execution of it. He laughed with joy.

“Why do you laugh?” said a voice behind him.

It was Pauline, who had returned. She had given the instructions to the patrol.

“An idea,” he replied—“a notion that appealed to me.” And then he perceived that he must at all costs get rid of Pauline, and he continued: “My sister is extremely disturbed,” he said. “Will you not, as a last favour, go and stay with her? Do not refuse me this. I will find some one to assist me in my work here—one of my trombone-players on whom I can rely. I—I really do not care for you to be out here like this. The strain is too much for you.”

“But Rosie——” she objected again.