It was late in the afternoon, when Dr. Hartmann, through his man Mayer, discovered that Seltz had left London, and should have appeared at his office with the snuff box during the forenoon. A description of Seltz, together with a curious feeling of uneasiness which he felt after the departure of the man who had introduced himself as Mr. Brooks, caused him to conclude that he had been made the victim of a clever trick, and one which only his professional enthusiasm had made possible.

He at once set to work, through Mayer and his men, to locate Brooks. This was done, without difficulty, at the Hotel Metropole. While the doctor followed the latter to the Minister's, firm in his belief that he carried the snuff box with him, Mayer had arranged through certain connections with the Belgian police, to have Dufrenne arrested and placed in confinement over night on a trumped-up charge; Seltz liberated, and Lablanche held on a pretense of being concerned in the theft from the latter of a valuable package. A thorough search of Duvall's baggage—Dufrenne, it seemed, had none—disclosed nothing, except certain documents setting forth that the latter was Richard Duvall, an American citizen. It was these papers, in fact, which Duvall had shown to Mr. Phelps earlier in the day.

There was nothing to indicate to Hartmann that Duvall was acting in the interests of the French secret police, but the doctor suspected it, knowing as he did that the recovery of Monsieur de Grissac's snuff box would become at once a matter of the utmost moment to Lefevre and his men. Curiously enough, his momentary suspicions of Grace had largely disappeared. There was nothing to connect her with Duvall. He did not know that it was she who had opened the door and admitted Seltz to his house earlier in the day—he thought that Duvall had done this himself. Grace's manner, her conduct during the ride in the cab from the Minister's house, had shown him nothing. Still, he felt that she would bear watching and made his plans accordingly.

The sun was shining through the windows of Duvall's room when he awoke the next morning. For a brief space he was unable to recognize his surroundings, then the sequence of events came to him with a rush. He was conscious of a knocking at the door. He sprang up and opened it. Outside stood one of the men attendants whom he had seen the night before, with the portmanteau containing his clothes. The man placed the bag upon a chair, and opened it, then withdrew.

Duvall proceeded at once to dress. He had just finished when the attendant returned with an elaborate breakfast on a tray. He ate heartily. Evidently the doctor had no intention of starving him. Upon the table he observed his watch and seals, which he had worn with his evening clothes the night before. He looked at the watch and saw, to his astonishment, that it was after nine o'clock.

Now that he was dressed, he wondered what he should do with himself. It did not occur to him that the doctor would do other than keep him confined to his room, yet the man who had brought the breakfast things had not apparently locked the door when he went out.

Without any clear idea of what he intended to do, Duvall went to the door and tried it. To his surprise, he found it unlocked, and in a moment he had passed out into the hall.

The house seemed deserted. Even the attendant who had sat at the head of the stairs the night before was no longer in evidence. He went down to the lower floor without seeing any one. As he passed the door of the doctor's office, on his way to the entrance, he heard it open, and Dr. Hartmann looked out at him with a grim smile. "Ah—going for a stroll, I see, Mr. Duvall," he said, pleasantly enough. "It's a fine morning. I hope you enjoy it."

Duvall made no reply. He appreciated fully that Hartmann was only making fun of him, and realized his helplessness.

Once outside the door, he paused for a moment to drink in the beauty of the morning. Straight ahead of him stretched the driveway which led to the main road. The ornamental iron gate stood invitingly open. He went toward it, unconsciously pondering upon his situation and what he could do, if anything, to escape from it. At the gate he paused, looking about carefully to see whether his movements were observed. There appeared to be no one near him, although along one of the paths to the right of the house, he saw several persons walking, whom he judged to be inmates of the place. One or two others sat on benches among the shrubbery, reading. None of them seemed to take the least interest in his movements.

An empty cab passed slowly, the driver on the lookout for a fare. For a moment the detective thought of escape, his hand came up with a jerk to signal the cabman, then suddenly he let it fall with an exclamation of dismay. He could not escape—he did not dare attempt it, knowing that the snuff box, which had already caused him so much anxiety and trouble, lay in a corner of the room beneath the doctor's laboratory. First he must get that, before he could attempt to escape. He turned slowly back toward the house.

Then suddenly another doubt assailed him. Had not Dr. Hartmann allowed him this liberty merely to see whether or not he would take advantage of it? Would the latter conclude, now that he had failed to do so, that the snuff box was hidden somewhere on the premises? The thought disturbed him greatly.

Still another consideration occurred to him. If he made any attempt to recover the box, would his doing so not show his captors at once that they had overlooked the hat—a chance, indeed, in a thousand? The first move he might make toward the room under the laboratory, would arouse Hartmann's suspicions, a search would be made and the hat and its precious contents discovered.

Certainly he was tied hand and foot. He dared not leave the place, without taking the snuff box with him; he dared not attempt to recover it for fear its hiding place would thereby be disclosed. He was, he suddenly realized, as much a prisoner as though he were locked in a cell. And Grace?

The thought of her caused him to glance about nervously, and in a moment he saw her coming toward him from the direction of the house. She appeared to be looking for him, yet when she saw him, she seemed in doubt as to what to do. Duvall went up to her. "Good-morning, Miss Ellicott," he said, in a voice clearly audible within the house, were any of the windows open. He fancied he detected Hartmann's dark face peering at him from the waiting-room.

"Good-morning, Mr. Brooks," she said, affecting great surprise at seeing him. "You are here still?"

"Oh, yes." His tone was careless, but as he spoke he moved in a direction away from the house, and toward a small bench that stood beside the driveway. "Dr. Hartmann concluded that I needed treatment—I'm afflicted with loss of memory, it seems. Beautiful day, isn't it?"

She murmured some response, waiting for him to speak again. Presently he judged the distance from the house sufficiently great. No one was near enough to possibly overhear them.

"The snuff box is hidden—sewn inside of the false crown of my opera hat," he said, in a low voice. "It is in the room under the doctor's laboratory. He does not know it is there, and I don't dare try to get it, for fear he will find out. If you have a chance—" He paused.

"I understand."

"But be careful—very careful."

"I will." They sat down upon the bench toward which they had been headed. "I had thought of seeing Mr. Phelps to-day, and asking him to have you released."

"It would be useless," he said. "I cannot go without the snuff box."

"Shall I send word to our friends in Brussels?" she asked.

"How can you do that?"

She explained the method, by means of the boy who drove the delivery wagon. He considered the matter carefully. "Let them know that I am here, and why I cannot escape. Tell them that the snuff box is safe—so far. Do not let them know where it is—I trust no one with that—except you, dear."

The tenderness of his voice thrilled her. She longed to grasp his hand—to tell him of the love which filled her heart. Suddenly he spoke, quickly, warningly. "Be careful," he said. "We are being watched. That man Mayer is observing us with an opera glass, from a window of the house. Don't look at me that way. I shall leave you now. Let us meet during the afternoon." He rose, bowed to her carelessly, and strolled back toward the house, leaving her disconsolate upon the bench.

He entered the hall aimlessly, not knowing what to do next. The situation was one which taxed his resources to the utmost. No case that he had encountered in his whole experience offered the slightest suggestion whereby he might hope to effect a solution of his present difficulties. Courage, resource, ingenuity seemed alike useless. He was helpless.

Dr. Hartmann appeared in the hall as he entered it. "Come in, Mr. Duvall," he said, holding open the door of the office. "Suppose we have a little chat."

For a moment the detective hesitated, then decided to meet the doctor's good nature in kind. "By all means," he replied. "You owe me some explanation of your conduct in keeping me here."

"Keeping you here, Mr. Duvall? Surely you are mistaken. The gate is open." He waved his hand toward the lawn.

"I have no desire to run away, like a criminal, Dr. Hartmann. When I go, I shall go in a dignified way, and take my belongings with me."

"Your belongings!" The doctor seemed impressed with the remark. "So you have the snuff box hidden somewhere among them, have you?"

Duvall began a hasty denial, but the doctor cut him short. "Absurd, Mr. Duvall," he exclaimed. "You would leave here quickly enough, if you could take the box with you. But where you have concealed it, I confess I cannot imagine. I have examined your things with the utmost care. It is not among them, of that I am certain. I gave you your liberty this morning, to see whether or not you would attempt to escape. Had you done so I should have known that the box was concealed somewhere in the city, or else in the hands of your confederates. Now I am convinced that it is here. I thought at one time that you might have given it to Miss Ellicott—I have an idea that there is something between you, although of that I am by no means certain. But I know that she hasn't it, for her belongings were searched with equal care, last night, while she slept. The thing is a mystery to me, Mr. Duvall, and I compliment you upon your ingenuity. Had you been as wise, yesterday, as you were clever, you would have left Brussels before I discovered the trick you had played on me. Why you did not do so—why you foolishly remained to dine at the house of Mr. Phelps, I confess I cannot see. It is beyond me. But all that is beside the case. You have the snuff box—at least you know where it is. Are you going to turn it over to me, or must I force you to do so?"

Duvall listened to the doctor with an impassive face. "I know nothing about any snuff box," he returned, with a show of anger. "You are wasting your time, Dr. Hartmann. I have nothing more to say on the subject." He turned his back and gazed moodily out across the lawn.

Hartmann regarded him with a scowl of anger. "I give you until to-night, Mr. Duvall, to do as I ask. After that, I shall be compelled to force you to do so."

The detective shrugged his shoulders and turned to the door. "You use strong words, my friend. If any harm comes to me, my government will know how to deal with you." His threat did not seem to alarm the doctor particularly. "Do not forget, Mr. Duvall," he said, with an evil smile, "that while I know how to cure mental disorders, I also know how to create them. Good-morning."

The grave threat in his words filled Duvall with uneasiness. What did Hartmann mean? Did he propose to feed him with drugs, cunningly concealed in his food, which would steal away his senses, and leave him a babbling child? The thought was terrifying. Yet he had until to-night. He decided to return to his room and think, hoping thus to evolve some plan which might prove a solution of his difficulties. In the afternoon he would communicate it to Grace, and she, in return, could send word to Dufrenne, so that the latter might coÖperate with him.

He found everything in his room as he had left it, and, seating himself by the window, was soon plunged in deep thought. The arrival of one of the attendants with his luncheon some two hours later woke him from a maze of profitless scheming. The problem was as yet still unsolved.

After luncheon, he decided to go down and have a talk with Grace. By keeping away from the house, and walking through the shrubbery, he hoped to be able to talk with her more freely. Much to his surprise, he found the door of his room once more locked. He sat down with a feeling of utter helplessness. The net was beginning to close about him.

Dinner was brought in at seven, and with it a small bottle of claret. He made an excellent meal, in spite of his unhappy reflections. The claret proved a welcome addition to it. On the tray was also a cigar. Decidedly the doctor was thoughtful, he reflected grimly.

Shortly after dinner he began to feel strangely drowsy. For a time he resisted the feeling—fought against it, but his eyelids seemed weighted with lead. Try as he would, he could not keep his eyes open. He threw up the window, gasping at the fresh air, but it had little effect. He rushed to the door, tried it, found it locked as he had expected, then groped toward the bed and fell heavily upon it, drunk with sleep. "It must have been the wine," he muttered to himself, and in another moment his muscles relaxed and he lay unconscious.