When Richard Duvall left the Hotel Universelle, en route to the office of Dr. Hartmann, he had no definite idea of just what he intended to do on reaching there. One thought was uppermost in his mind—he must prevent, in some way, and at any cost, the delivery of the snuff box to Hartmann, and since to follow Seltz to the latter's office would avail him nothing, he decided to precede him there.

During the drive, he began to formulate a plan, daring in its conception, extremely dangerous in its execution, yet one which, if carried out with courage and determination, promised success. He was perfecting in his mind the details of this plan when the carriage turned into the driveway at Dr. Hartmann's.

So occupied had he become with his thoughts that he failed to observe the figure of Grace, standing behind the maid in the open doorway; she disappeared into the reception-room before he had alighted from the cab. He went up to the servant, assumed an air of dignified assurance, and announced that he wished to see Dr. Hartmann at once.

The maid ushered him in, glanced into the parlor, observed Grace sitting there, apparently reading, and then throwing open the door to the left which gave admittance to the doctor's office, bade Duvall enter. The latter stepped in at once, without looking into the room across the hall. Had he done so, he would have observed his wife, whom he fully supposed to be quietly waiting for him in Paris, rise from her chair with a frightened face and start impulsively toward him.

For a moment Grace was on the point of calling out—she wanted to let Richard know that she was there. She wanted to see him—to talk to him, to realize the happiness of being once again in his presence. It had been, since their parting the day before, her constant thought. Then she suddenly realized that Monsieur Lefevre had warned her not to appear to recognize her husband, should she meet him in the course of her adventures. The thought checked her—she paused at the door of the reception-room and glanced down the hall.

The servant who had admitted Duvall had disappeared toward the rear of the house. Everything about her seemed quiet. She started across the hall, determined to enter the room into which Richard had just vanished, when she heard the sound of rapid footsteps approaching her. With a start she turned and again entered the parlor, assuming a careless manner she by no means felt.

She had scarcely seated herself in the chair by the fire, and opened her book, when she saw Dr. Hartmann appear in the hall and enter the door which led to the outer office.

Grace was undecided as to what she should do next. Her safest course, she ultimately concluded, was to do nothing. She remained quietly in her seat, pretending to read her book, but all the while watching, with anxious eyes, the door on the other side of the hall.

Richard Duvall, meanwhile, had entered the waiting room, his mind fully made up as to the course he was about to pursue. During the few moments which intervened, until the doctor's arrival, he looked keenly about the room, examining it in detail, fixing its entrances and exits firmly in his mind, so as to be prepared for any emergency which might arise.

The room was a large one. Along the side facing the entrance door, as well as that which fronted on the park, were big curtained windows, set in deep recesses, and between them, cases of books. At the far end of the room, toward the rear of the house, was another door. Duvall stole over to it, listened carefully, then slowly opened it and looked within. The room proved to be the doctor's private office, and he saw at once that it was built in a sort of ell, and could not be entered except through the room in which he stood. There was a door, it is true, in the right-hand wall, which had once given entrance to the hall, but against this a heavy instrument case, with glass doors, now stood.

Duvall withdrew his head and shoulders from the doorway, nodding to himself in a satisfied way, then noiselessly closed the door and returned to the center of the room.

In a moment Dr. Hartmann came in, glancing at him sharply. "Good-morning, sir," he remarked, in French. "You wish to see me?"

The detective took a card-case from his pocket and tendered the doctor a card. It was one of many which he carried for such emergencies, and bore the name of Stephen Brooks.

"Yes," he said, pleasantly. "I came to consult you concerning a curious case."

"Indeed!" The doctor looked at the card carelessly. "I see that you are an American." He began to speak in English. "Sit down, please."

"Thank you." Duvall took a chair.

"What is the nature of the case, may I ask?"

"Doctor—I've heard so much of your wonderful cures—of your remarkable success in treating mental disorders, that I have ventured to come to you in the hope that you may be able to help me."

The doctor smiled, not displeased at the other's flattery. "What is the cause of your trouble, Mr. Brooks?"

Duvall observed him thoughtfully for a moment. "If a person has delusions upon one particular subject, is he on that account necessarily insane?"

"Not at all. Manias of various sorts are not uncommon, and generally curable. Why do you ask?"

"Because I want you to treat such a case."

The doctor considered his patient narrowly. "Of course, you understand, Mr. Brooks, that my professional charges are very high."

Duvall took out his pocketbook and removing from it a note for a hundred francs, laid it carelessly on the table. "I have understood so, Doctor," he remarked. "Luckily I am a man of considerable wealth."

"In that event," Hartmann remarked, eying the bill in a gratified way, "I am at your service. What is the nature of your complaint?"

"It isn't about myself that I have come," Duvall hastened to inform him. "It concerns a man in my employ—my valet, to be exact."

"Your valet?" The doctor frowned, and made as though to rise. "My dear sir—"

"One moment, please, Doctor. The man is a most worthy fellow. He has been in my service for years. A Belgian, too, I think. I have a very high regard for him—an excellent servant, except for the peculiar delusions with which he has lately become possessed."

"I fear that I cannot undertake his treatment, Mr. Brooks. I receive only a few patients, and those of the highest standing."

"I know that. I did not propose to have the man quartered here in your house. I merely want you to examine him, in order that I may find out whether his case is curable or not. If it is, I shall take him to Paris and place him under treatment—if not, I must, of course, discharge him. It is for that reason that I have come to you."

"What are the man's symptoms?" asked the doctor, shortly.

"He imagines, from time to time, that he has been robbed."

"That is by no means uncommon. I have seen many such cases. Are these delusions confined to any one subject?"

"No. At times he fancies that money has been taken from him. At other times, jewelry that he has never possessed. Once he accused me of robbing him of a pair of shoes, and demanded that I pay him a large sum of money for them. I have generally succeeded in quieting him by assuring him that the stolen articles would be forthcoming later on."

"Excellent. And how long has this condition been in evidence?"

"About a month, now. During the past week, however, the attacks have been more frequent. Last night he informed me that someone had taken from him a diamond ring—of course he had never owned one—and wanted five thousand francs in return. I assured him that I would get him the money this morning."

"The case does not seem particularly difficult, Mr. Brooks, from what you tell me. Of course I could determine better after a personal examination."

"Exactly. And if you find no other conditions of an alarming nature, you think a cure possible?"

"Undoubtedly. When can I see the man?"

Duvall took out his watch. "I requested him to meet me here to-day at noon," he said. "I did not tell him he was coming for a medical examination. He might have refused to come. I let him think that you might be able to recover the diamond ring he thinks has been stolen from him. I thought it best to humor him. I should have brought him with me, but he had arranged to go this morning to see his people, who live in the town. He was to come directly here, after leaving them." He went over to the window and looked toward the road. "I am surprised that he is so late. Usually he is punctuality itself."

The doctor rose. "No doubt he will be here very soon," he remarked. "You can wait here, if you like. I will join you on his arrival. Meanwhile, as I have some matters to attend to in my office, I beg that you will excuse me." He opened the door at the rear of the room, which led to his private office. "When the man arrives, kindly let me know."

Duvall glanced toward the door through which Dr. Hartmann had just passed, then paused for several moments, listening; then he walked noiselessly across the room, and paused before the study door. Within all was quiet. Stooping down, he applied his eye to the keyhole. Dr. Hartmann sat at a large rosewood desk, busily writing.

With a smile of satisfaction the detective arose, and going to the door which led to the hall, drew from the lock the key which stood in it, and then, opening the door slightly, inserted the key in the lock on the other side of the door. As he did so, he peered out across the hall, and for a moment the key almost dropped from his fingers. There, facing him, sat Grace, his wife, whom he had supposed to be safely in Paris. The sight for a moment completely upset him—he paused, gazing at her with an expression of incredulity.

Grace rose, and came toward her husband, her face pale, her lips parted. "Richard," she whispered softly, then became suddenly silent as he pressed his finger to his lips.

As they stood there thus, facing each other in grave uncertainty, Duvall heard the sound of a vehicle being driven up the graveled road. He glanced toward the glass entrance door and saw a cab approaching the house, in which sat Seltz. He turned to Grace, and spoke in a voice so low as to be scarcely audible.

"Open the door at once—before the man can ring. Pretend to be a maid. Show him in here immediately. Quick." He withdrew into the waiting-room, leaving Grace staring at him in amazement. For a moment she hesitated. It seemed so cruel, to be this near to him, and yet to not even be able to touch his hand! Then she went quickly to the front door and threw it open as Seltz came up the steps.