Richard Duvall, realizing that the woman he sought had once more eluded him, was for the moment unable to decide what to do next. He was oppressed by a sense of failure. Apparently this enemy of Ruth Morton\'s was far more resourceful than he had supposed. She had gotten clear away, and there appeared no means by which he could trace her. That the second cab, the one he had hailed, contained Grace, did not of course occur to him. The trail appeared to be hopelessly lost.

Still, his investigations in Miss Ford\'s room had not been entirely fruitless, although they had also added a startlingly new element to the mystery of the case. Who was the person who had attacked him from the closet? Was it the woman who had just left the house? He did not think so. Nor was it Miss Ford herself. There had been something uncanny about the whole experience; he was by no means certain that his assailant had been a human being at all. And yet, its cries—its fingers, tearing at his throat. He was unable to account for the experience at all, and determined, as soon as possible, to repeat his visit, and sift the matter to the bottom.

He remembered that he had seen two persons in the Ford girl\'s room, after his hasty retreat. Two women, he thought, outlined against the lighted square of the window. One of these had already left the house. The other, Miss Ford herself, was still there. He determined to interview her at once.

Of course, he told himself, to do so would put her on her guard, but his visit to her room had already done that, and doubtless accounted for her companion\'s hasty flight. And there was something to be gained, by letting her realize that she was under suspicion. She would at once try to communicate with, to warn, her confederate, and it was in just such ways as this, Duvall\'s experience told him, that criminals so often betrayed themselves. If, by frightening Miss Ford, he could cause her to flee—to join her companion—the tracing of the latter would become comparatively simple. He went up to the door of No. 162 and rang the bell.

The same woman answered his summons as had answered before. She seemed somewhat uneasy—disturbed.

"I want to see Miss Marcia Ford," Duvall told her.

"Very well, sir. Come in. I will tell Miss Ford. What name, please?"

"Say that Mr. Bradley is calling."

The girl ushered him into a dark parlor, lighted by a single lowered gas jet, and suggestive of the gloom of ages, in its walnut furniture, its dismal pictures and ornaments. He took a seat, and waited for the appearance of Miss Ford.

She arrived in a few moments, a slender, ordinary-looking girl, in white shirtwaist and black skirt.

"You are Mr. Bradley?" she asked, regarding the detective with a look of inquiry.

"Yes. I came to see you about a matter of importance."

"What is it?"

"Who was the woman who just left here—the woman who had just come in with you?" Miss Ford favored the detective with a glassy stare.

"I do not understand you," she exclaimed. "I came home alone. What is the purpose of these questions?"

Duvall felt that he had a shrewd opponent to deal with.

"Are you acquainted with Miss Ruth Morton?" he asked.

"Why—certainly—that is, I know her by reputation, She works for the same company as I do. Why do you ask?"

"Miss Morton has recently been the subject of a shameful persecution. The woman who just left this house is concerned in it. Who is she?"

"I do not know what you are talking about," the girl exclaimed, angrily. "I know nothing about any woman. You must pardon me, Mr. Bradley, if I decline to be questioned in this way any further." She moved toward the door.

"Then you wish me to understand that the woman who just left this house did not come here with you?"

"Understand anything you please. I decline to be questioned any further." With a look of anger she left the room.

Duvall made his way back to the sidewalk, thoroughly satisfied with the results of his visit. The Ford woman, in the first place, had lied. The other woman had been with her, beyond a doubt. Duvall thought of her picture on the wall of Miss Ford\'s room. The latter\'s reason for lying was equally clear. She and the woman with her were guilty.

In the second place, Miss Ford now realized fully that she was under direct suspicion. If, this being the case, she failed to take some step that would be fatal to both her confederate and herself, Duvall felt that he would be very much surprised. He made up his mind to keep close watch upon the house.

Suddenly it occurred to him that Grace might be of immense service to him at this juncture. She could follow the Ford girl, unknown, unrecognized, while he himself could not. He decided to call h............