The house was, like that which immediately adjoined the apartment building, an old-fashioned one, of brown stone, with a high front stoop. It presented an appearance which, if not exactly dilapidated, was yet in strong contrast to the neat appearance of its neighbors. A printed card in one of the lower front windows indicated that roomers were wanted.

It was just the sort of place that Duvall had expected to find—just the sort of place in which a working girl like Marcia Ford would live. Located in a very excellent neighborhood, surrounded by apartment buildings and houses of the best type, it still could afford to rent rooms at the moderate figure that one of her class could pay. He went up the front steps and rang the bell. "Is Miss Ford in? Miss Marcia Ford?" he asked.

The servant who came to the door, a neatly dressed German girl, shook her head.

"No, Miss Ford is not in. She usually gets back about half past six."

Duvall glanced at his watch. It was not yet three o'clock. He realized that he had a long wait before him.

"Will you leave any message?" the girl asked.

"No. It is not important. I will come back." Descending the steps he walked slowly in the direction of the apartment building, two doors away.

Entering, he made his way to Mrs. Morton's apartment. The place was just as they had left it, two days before. The windows had all been tightly closed and fastened, and there were no further mysterious messages lying about. Once more Duvall went to Ruth Morton's room, and opening the two windows looked out.

His investigations, however, told him no more than he had learned before. The three dormer windows in the home next door gazed vacantly down at him, their windows covered with cobwebs and dust. The impossibility of anyone making their way from even the nearest of them, to the window where he stood, was manifest. And that a long rod or pole could have been utilized to introduce the letters into the girl's room was even more impossible. He shook his head, then turned to the other window, that facing upon the fire escape.

Here, as on the occasion of his previous examination, the smooth glossy surface of the freshly dried paint showed no marks, except those he had himself made during his former visit. And yet, as his eyes searched the grated surface, he saw that there was something there, something that had not been there before. He reached out and picked it up.