"He's still asleep," laughed the detective, then explained to the others, in a few words, his adventure of the morning. He saw that the Minister was puzzled, but the latter said nothing, at the time, and in a few moments the matter was forgotten. Only Grace showed any signs of alarm—Duvall went calmly on with his dinner as though nothing had happened. He spoke to her only occasionally and then addressed her with the formal politeness of a total stranger.
Dr. Hartmann was observing him intently under cover of a spirited conversation with Mrs. Phelps. It was clear to Grace that he could not quite understand why Duvall, or Brooks, as he supposed him to be, was dining here at the Minister's.
It was quite late when the party rose from the table, and, a little while later, Grace, anxious to get away from the place, and be alone with Richard, announced that she must return home. "Mr. Brooks has kindly offered to escort me," she said, quickly, fearful that Dr. Hartmann might suggest that she return with him.
The latter smiled coldly, his eyes fixed on her with a gleam of suspicion. "I think I shall be going myself," he said, as he took leave of the remainder of the party.
As they reached the sidewalk, Duvall observed the taxicab he had ordered to be in readiness, standing in front of the door. He helped Grace inside, then turned in some hesitation to the chauffeur. He dared not tell the fellow to drive to the railway station, since Hartmann, who stood beside the cab chatting with Grace, would inevitably hear him. He therefore instructed the man to go to Dr. Hartmann's with the intention of countermanding the order a little later, as soon as they had got out of earshot of the house. He threw open the door, entered the cab, and was about to pull the door shut after him when he felt his wrist seized from behind in a powerful grasp, and before he realized what had happened, Dr. Hartmann had stepped into the cab and closed the door. The chauffeur at once started off at a great rate.
"I'm sure, Mr. Brooks," said the doctor, suavely, as he sat down in the forward seat, his right hand still grasping Duvall's wrist, "that you will not mind taking me home with you. It is a long walk, and I fear there are no other taxicabs in sight."
Duvall looked at him sternly, then attempted to draw away his hand. "What do you mean, monsieur," he asked, harshly, "by detaining me in this manner?" He again tried to free his wrist, but the doctor was too strong for him.
Hartmann smiled pleasantly. "I feared, Mr. Brooks," he said, "that you might be tempted to use the revolver which you have in the pocket of your coat." He reached over quickly with his other hand and drew the revolver from the detective's pocket.
Grace, through all this, had said absolutely nothing. She realized how fatal any interruption by herself might be. She did not know of her husband's intention to leave Brussels that night. She had heard him order the chauffeur to drive to the sanatorium. Perhaps he wished her to return there. In that event, it was imperative that Dr. Hartmann should not know that the supposed Mr. Brooks and herself were anything but the most chance acquaintances.
"Doctor," she cried out, "what are you doing?"