When at last it was fitted and stealthily turned with an attempt at noiselessness, the door refused to yield. That, he told himself furiously, he might have expected. For all their seeming sense of security they had reenforced it by shooting the bolt on the inside so that no one could enter without sending an alarm ahead of his coming. It was only one proof more of guilty concealment within. But it was far past time for needing such corroboration. He had seen enough and the problem raised by the present discovery was quite another. He went about the place trying side doors and windows, but everywhere his house was closed against him--and that meant a complete revision of plan, and the relinquishment of the tremendous force of climax to be gained by slipping in unannounced and holding over confounded evil-doers the irrefutable proof of demonstration. He must knock on his door, and give them time to slip back into their disguise of hypocrisy. It meant that, in the principal feature, his whole carefully laid plan had failed, but at least now he knew the truth and was ready to let the avenging bolt fall. They would meet him with smiles of innocence: they with sinful kisses yet warm on their lips. They, fresh from their interrupted love, would talk casually. Very well, for a little while yet he could smile and be casual, too, meeting their guile with counter dissembling--until he was ready. * * * * * If Stuart Farquaharson had been sitting most of that evening in a darkened room, it was because his misery was so great that the light seemed to make clearer the wretchedness of his future. For a time he had tried to read; even to write, but that was before Eben had come. In all those efforts he had failed and now for more than an hour he had been gazing dejectedly out of the window, listening to the wind as it buffeted itself out and died in an exhausted moaning among the pines. He had heard the wailing of the harbor sirens but his eyes had been unseeing--at least unrecognizing. And Conscience had been writing the letter which she meant to leave under the door of Stuart's room. He would find it there in the morning, and when he said good-by, he would understand the things which she had left unsaid before they parted in the hall. She _had_ gone and left the letter at the door: had even listened there a moment, unknown to the room's occupant, and it was that crossing of her threshold which her husband saw. Then Stuart had switched on his light, and thrown off his clothes. If he seemed calm as he lighted his pipe, it was a calm of spent emotion, and not the complacency of a man who awaits a tryst. Through the stillness of the house the hammering of the brass knocker sounded loudly. Stuart Farquaharson in his room and Conscience in hers, both heard it, with a sense of astonishment. The man opened his door and hurried to the stairhead, where he found Conscience, arrived in advance of him.