"Then we must leave him in the care of Monsieur Lefevre's other agents here in Brussels. We cannot delay an instant, on any account."

"I do not agree with you, monsieur. There is one thing which is as important to me as the recovery of the snuff box could possibly be to Monsieur de Grissac, and that is, the safety of my wife."

"Your wife?" Dufrenne stared at him in surprise.

"Yes, monsieur, my wife. She is at present in Dr. Hartmann's house. How she came there, I do not know, but I imagine that our friend the Prefect sent her there, to assist, if occasion offered, in our work. In that he was wise; but for her presence, I fear my plan would have failed. Had Seltz rung the doorbell, and been admitted by any of the doctor's servants, I doubt if I should have been able to get the box from him before the latter had seen him. I should then have been obliged to use force, and the results might have been disastrous."

"Yes, monsieur. I see that. The young lady at Dr. Hartmann's was sent by Monsieur Lefevre. His agents here have already informed me of that. But that she is your wife I did not know." He pondered for a moment, glancing at his watch. "It is a great pity. Delay may be most dangerous. Why do you not send her word to join you in Paris?"

Duvall frowned, and began to walk about the room nervously. "A few hours' delay can make no difference," he presently said. "The box is perfectly safe in our hands. I am not, however, at all convinced that my wife is perfectly safe in the hands of Dr. Hartmann."

"But he knows nothing?"

"That I cannot say. So far he does not, I think, suspect that Seltz was the man he expected from London. If he had, he would never have let me leave his office. Luckily for us, Seltz was a stranger to him, and with the murder of Noël on his conscience, he feared to say anything to the doctor about the snuff box while I was present. I imagine he suspected a trap of some sort. But the doctor will discover, probably before the day is out, how he has been tricked. Then he will begin to investigate, and if he finds out that it was my wife who admitted the man, he may in his rage decide to retaliate upon her. I cannot think of leaving Brussels, without her. She must go with me. Upon that I am determined."

Dufrenne looked grave, and a glint of anger came into his eyes. "The service of France, monsieur, is more important than your private affairs. I beg of you that you leave here at once."

"But why, my friend? We can leave just as well in the morning. The box is safe." He felt his waistcoat pocket.