When Grace arrived at Dr. Hartmann's that night, she was so utterly astonished by the course which events had taken that she was scarcely able to think. What to do she could not even guess. Here was her husband, the man she loved, in the power of Dr. Hartmann, and there seemed nothing whatever that she could do to help him. Yet how could she go quietly to her room, when Richard might be in the gravest danger? On the other hand, to attempt any resistance, to let the doctor know, by any action on her part, that she and Duvall were working in conjunction, would result in nothing but further disaster. The thought flashed through her mind that by preserving her character of a patient, she might, in the morning, communicate with Mr. Phelps, and secure his assistance in obtaining Richard's freedom.

These considerations came and went in the few seconds required for the little party to enter the hall. Her husband went first. Dr. Hartmann stood aside to permit her to follow him. Duvall turned as she passed through the door, and she heard him whisper, in a voice scarcely audible, "Say nothing." It was the cue she desired. She extended her hand as the doctor came in. "Good-night, Mr. Brooks," she said, quite calmly. "Thank you for bringing me home. I hope we shall meet again, sometime."

"I hope so," Duvall remarked, indifferently, then turned to the doctor. "Now, monsieur, let us have done with this farce as quickly as possible. I have no time to waste."

"Nor have I. Good-night, Miss Ellicott." He nodded pleasantly to Grace as she ascended the stairs, then addressed one of the two attendants. "Where is Herr Mayer?" he asked.

"He is waiting for you in the laboratory, Herr Doctor," the man replied.

"Good! This way, if you please." He motioned down the hall. "Be so good, Mr. Brooks, as to proceed at once."

Duvall started off down the hall in no pleasant frame of mind. The whole affair had been bungled by his stupidity. He passed through the door which Hartmann presently opened at the end of the hall, and found himself in a long narrow passage, lit by a single electric lamp. Hartmann closed the door carefully behind him, and came on down the corridor, his footsteps echoing loudly on the concrete floor.

At the end of the corridor a second door confronted them. It was opened by a tall blond man, with a reddish mustache and brilliant blue eyes. "I heard you coming," he said, nodding to Hartmann, then looked keenly at Duvall. "So this is the fellow, eh? Where shall we take him?"

The doctor pointed to an iron door which faced that by which they had entered. Between the two doors ran a narrow corridor, with an iron staircase to the left, leading upward. "In here," he said, shortly, and going to the door, opened it with a key which he drew from his pocket.

Again Duvall cursed his stupidity. For a moment, thoughts of resistance crossed his mind but he at once realized the hopelessness of it, and followed the doctor into the room. The tall man brought up the rear, closing the door silently after him.

The room was pitch dark. In a moment, however, Hartmann had pressed an electric button, and a brilliant light flooded the place. Duvall looked about him curiously, and in that fleeting glance saw that the room was without windows of any kind, and that the walls, smooth and white, contained no openings whatever, except the door by which they had entered. The floor, as he could tell by its feel under his feet, was of cement. The room was bare of furniture, but he perceived a number of boxes and packing cases standing about the walls.

The instant the door was closed, Hartmann sprang at the detective and grasped his two wrists. The latter had always been considered a powerful man, but the arms and shoulders of the doctor were those of a Hercules. "Search him, Mayer," he said, as he pinned Duvall's wrists together in his iron grip.

The man addressed as Mayer at once began a systematic search of Duvall's person. With deft fingers he explored his pockets, felt the linings of his clothing, tore through the contents of his pocketbook. The opera hat had fallen to the floor, in the short struggle which ensued when the detective found himself in Hartmann's grasp. Mayer picked it up, glanced at it carelessly, then threw it angrily into a corner, where it rolled unobserved, into the shadow of a large box.

"There is nothing here," he said, in a voice of keen disappointment. "He must have hidden it elsewhere."

"In his room at the hotel, perhaps—his portmanteau," the doctor said, eagerly, releasing Duvall's hands and throwing him to one side with some violence.

Mayer looked grave. "I have searched everything thoroughly. It is not there."

The doctor muttered an oath. "The other—the old Frenchman?"

"He was arrested to-night on a charge of irregularity in his passport. Nothing discovered. He will be released in the morning."

"Teufel!" The doctor swore excitedly in German. "Then the other one—the one who was in charge of Seltz—he must have it."

"No. He also has been searched, with the same results."

"May I ask what you are looking for?" asked Duvall, calmly.

"You know, well enough, Duvall," exclaimed Mayer, turning on him. "Oh, yes—I know your name. The examination of your baggage showed that. As soon as I wired to London and discovered that the man Seltz had left there last night, I knew how we had been fooled. One of our men saw the snuff box in your possession just before you left the hotel to go to the house of Mr. Phelps. What have you done with it?"

Duvall regarded his questioner calmly. "I do not know what you are talking about, gentlemen. I have no snuff box, nor do I use tobacco in that form. And now, if you have concluded this outrage upon an American citizen, perhaps you will let me return quietly to my hotel. If you do not, I promise you you shall pay heavily for it."

His words, for the moment, seemed to disconcert the two men. Then Mayer laughed, "Nothing but bluff, young man—American bluff. I know who you are. You followed Seltz here from London, and got the snuff box from him by a trick. Now tell us where it is."

The detective smiled. "I do not know what you are talking about," he said, quietly.

Dr. Hartmann growled out an oath. "Take off his things, Mayer. He may have the box in his clothing somewhere—or the heel of his boot. I'll get a dressing-gown, from above." He left the room, and Duvall heard him clanking up the iron staircase.

"If you insist on removing my clothes," he said to Mayer, "I prefer to do so myself." He rapidly stripped off his evening suit and shoes, and threw them upon the floor.

The man gathered them up, feeling each article carefully, and testing the heels of the boots with a knife which he drew from his pocket. He appeared greatly disappointed at not finding the object of his search. Then he again examined Duvall, feeling his person from head to toe with great care. He had just finished when the doctor returned with a long gray woolen dressing gown, which he tossed to the detective.

"He's hidden it somewhere. He hasn't got it with him," Mayer exclaimed, angrily.

"Take him to the small bedroom in the west wing," said the doctor. "We'll get it out of him, before we're through. You can leave the clothes in the laboratory." He cast his eye about the room to see that nothing had been forgotten. Duvall trembled, thinking of the hat lying unseen behind the packing case in the corner. Hartmann, however, did not observe it. Without saying anything further he threw open the door, and they all passed into the little hall.

From there, Duvall was led up the iron staircase to the floor above, and found himself in a large room which he took to be the doctor's laboratory. It was dimly lit by means of a reading-lamp. He had a confused vision of a number of scientific appliances, bulking huge and forbidding in the shadows, and then was conducted through a glass door and along a corridor similar to the one through which he and the doctor had so recently passed on the floor below. He judged, from the direction they were taking, that it was directly above the lower passageway, and led back to the main part of the house.

In this he soon found that he was correct. A door at the end of the corridor gave entrance to the upper central hall of the main building. He was led off to the right, catching a momentary glimpse of a woman attendant sitting in a chair near the head of the stairs as he passed. In a few moments Hartmann paused before a door, threw it open, and turned on the lights. The detective saw before him a well-furnished bedroom, with two large windows, and another door, which he later found gave entrance to a bathroom. The dark shadows against the night light without showed him at once that the windows were barred.

He turned to the two men. "You do not intend to release me then?" he asked, angrily.

Hartmann laughed. "You will be quite comfortable here, my friend. I am sure that a few days of complete rest will benefit your condition greatly. I imagine your trouble is merely a temporary affliction—a loss of memory, let us say, an inability to recall your name. We'll soon have you all right again. You have only to inform me where you have placed the snuff box which you stole from my messenger this morning, and I shall know that a complete cure has been effected. If your friends are alarmed about you, it will be quite sufficient to tell them that you are in my care. Mr. Phelps, for instance, has complete confidence in my ability. I will make it a point to explain matters to him at once. Just a trifling ailment, a disordered condition of the brain cells. A week should set you right again. If there is anything you wish, the attendants will get it for you. Your clothes will be sent up from the hotel in the morning. Make yourself quite at home, I beg of you."

He turned away, with a sardonic smile, and Duvall heard the key turn in the door as it closed. He glanced at the barred windows, the door, half-open, leading to the bathroom, and realized that there was not the slightest hope of escape. Dr. Hartmann evidently intended to keep him a prisoner until he disclosed the whereabouts of the snuff box. He smiled grimly as he threw himself upon the bed. It seemed likely that his stay would be a long one.

After a time he began to think of Grace. How cleverly she had carried out her part! It was clear that the doctor did not suspect her, or, if he did, was unable to see where his suspicions led. How strange it seemed to realize that she, his wife, lay somewhere under the same roof with him—possibly even in the very next room! But thirty-six hours had passed since their wedding and their sudden and unexpected parting. During that time, he had seen Grace but twice, once, at Hartmann's office, in the morning; the second time, at the Minister's that night. How he had longed to touch her hand, to put his arms about her, to feel his lips on hers. Yet as matters stood, the chances of their seeing each other in the near future seemed particularly remote. He wondered if Hartmann would keep him a prisoner in his room. The morning, of course, would tell. He switched off the lights, got into bed, and after a long time fell into a broken sleep.