The last thing that sounded in Richard Duvall's ears as he left the office of Monsieur Lefevre, Prefect of Police of Paris, were the latter's words, spoken in a voice of mingled confidence and alarm, "The fortunes of a nation may depend upon your faithfulness. Go, and God be with you." He entered the automobile which was drawn up alongside the curb, and accompanied by Vernet, one of the Prefect's assistants, was soon threading the torrent of traffic which pours through the Rue de Rivoli.

The thoughts which lay uppermost in the detective's mind were of Grace, his wife; Grace Ellicott, who had become Grace Duvall but little more than an hour before. By this time he had expected to be on his way to Cherbourg, en route to New York, with Grace by his side. They had looked forward so happily to their honeymoon, on shipboard, and now—he found himself headed for London on this mysterious expedition, and Grace waiting for him in vain at the pension. The thought was maddening. He swore softly to himself as he looked out at the crowded street.

Monsieur Lefevre had no right to ask so great a sacrifice of him, he grumbled. What if he had distinguished himself, made himself the Prefect's most valued assistant, during the past six or eight months? The matters which had brought him from New York to Paris had all been definitely concluded—Grace and he were married—his plans had all been made, to return to America, and home. Now at the last moment, it was frightfully exasperating to have Monsieur Lefevre insist that matters of so grave a nature had occurred, that the honor of his very country was at stake, and to call upon him, Duvall, as the one man who could set matters right. Of course, it was very flattering, but he wanted, not flattery, but Grace, and all the happiness which lay before them. What, after all, was this matter, this affair so vague and mysterious, into which he had so unexpectedly been thrown? He drew out the instructions which the Prefect had hurriedly thrust into his hands, and looked at them with eager curiosity.

They covered but one side of a small sheet of paper. "Visit immediately number 87, Rue de Richelieu," they said. "It is a small curio shop. Monsieur Dufrenne, the proprietor, expects you, and will join you at once. Proceed without delay to London and report to Monsieur de Grissac, the French Ambassador. He has lost an ivory snuff box, which you must recover as quickly as possible. You will find money enclosed herewith. Monsieur Dufrenne you can trust in all things. God be with you.—Lefevre."

It was the first time that Duvall had read the instructions. He had not had an opportunity to do so before. As he concluded his examination of them, his face hardened, his brow contracted in a frown, and he crushed the piece of paper in his hand. Was this some absurd joke that Monsieur Lefevre was playing upon him? The idea of separating him from Grace upon their wedding day, to send him on an expedition, the object of which was to recover a lost snuff box! It seemed preposterous. In his anger he muttered an exclamation which attracted the attention of Vernet. He was, in fact, on the point of stopping the automobile, and going at once to the pension where Grace was waiting for him, her trunks packed for their wedding journey. The impassive face of the Frenchman beside him relaxed a trifle, as he saw Duvall's agitation. "What is it, Monsieur Duvall?" he inquired.

"Do you know anything about this matter that makes it necessary for me to go to London?" demanded Duvall.

"Nothing, monsieur, except that your train leaves—" he consulted his watch—"in twenty minutes."

Duvall drew out a cigar and lit it, with a gesture of annoyance. "The matter does not appear very important," he grumbled.

Vernet permitted a slight smile to cross his usually immobile face. "I have been in the service of the Prefect for ten years," he remarked, "and I have learned that he wastes very little time upon unimportant things." He leaned out and spoke to the chauffeur, and in a moment the car halted before a dingy little shop, on the lower floor of an old and dilapidated-looking house. "Here is the place of Monsieur Dufrenne," he remarked significantly.

Duvall threw open the door of the cab, and entered the dusty and cobwebbed doorway. He found himself in a small dimly lighted room, so crowded with curios of all sorts that he at first did not perceive the little white-haired old man who bent over a jeweler's work bench in one corner. The walls were lined with shelves, upon which stood bits of ivory and porcelain, miniatures of all sorts, old pieces of silverware, bronze and copper, old coins, and rusty antique weapons. About the walls stood innumerable pictures, old and cracked, in dilapidated-looking frames, while from the ceiling were suspended bits of rusty armor, swords, brass censers, Chinese lamps, and innumerable other objects, the use of which he could scarcely guess.

All these things he saw, in a queer jumble of impressions, as his eyes swept the place. In a moment the little old man in the corner turned, peering at him over his steel-rimmed spectacles. "You wish to see me, monsieur?" he inquired in a thin, cracked voice.

"Yes. I am Richard Duvall. I come from Monsieur the Prefect of Police."

The man at the workbench, on hearing these words, rose to his insignificant height, dropping as he did so the watch over which he had been working. He swept his tools into a drawer with a single gesture, turned to the wall behind him, drew on a thin gray overcoat and a dark slouch hat, and stepped from behind the counter. "I am ready, monsieur," he remarked, without a trace of agitation or excitement. "Let us go."

Duvall turned to the door without further words, and threw it open. The old man motioned to him to pass out, and after the detective had done so, closed and locked the door carefully and followed him into the cab. Duvall observed that he was frail, and uncertain in his steps, and so bent from constant labor over his bench, that he gave one almost the impression of being hunchbacked. He took his seat beside the detective without a word, and in a moment the whole party was being driven rapidly toward the Gare du Nord.

Duvall could not repress a feeling of admiration for the way in which Dufrenne had received him. He had asked no questions, delayed him by no preparations, but had merely thrown down his tools, put on his hat, and started out. The importance or lack of importance of the matters which called him he did not inquire into—it was evidently quite enough, that Monsieur Lefevre desired his services. It made the detective feel somewhat ashamed of his recent ill nature, yet he could not but remember that this was his wedding day, and that in leaving his wife without even so much as a farewell word, he had given her good reason for doubting his love for her. Of course, he knew, the Prefect had assured him that he would explain everything to Grace, but such explanations were not likely to appeal very strongly to a girl who had been married but little more than an hour. It was, therefore, in a very dissatisfied frame of mind that he entered the compartment of the train for Boulogne.

The compartment was a smoking one, and he and Dufrenne had it all to themselves. The little old Frenchman drew out a much-stained meerschaum pipe and began placidly to smoke it. His manner toward the detective was respectful, friendly indeed, yet he made no attempts at conversation, and seemed quite satisfied to sit and gaze out of the car window at the fields and villages as they swept by. Presently Duvall spoke.

"Monsieur Dufrenne," he began, slowly, "you are no doubt familiar with the matter which takes us to London?"

Dufrenne withdrew his gaze from the window and faced about in his seat with a nervous little gesture of assent. "I understand that Monsieur de Grissac has been robbed of his snuff box," he replied.

"Is that all you know?" Duvall inquired pointedly. "Surely the recovery of an article of so little consequence cannot be the real purpose of our visit."

The little old man shrugged his shoulders, with an almost imperceptible gesture of dissent. "I know nothing of the matter, monsieur," he remarked, significantly, "except that my country has called me, and that I am here." He spoke the words proudly, as though he considered the fact that he had been called upon an honor.

"But surely, you must have some idea, monsieur, of your purpose in being here?"

"Yes. That is indeed quite simple. On one occasion I was called upon to repair the snuff box of Monsieur de Grissac, the Ambassador. In that way I am familiar with its appearance. Now that it is lost, I am requested to accompany you, monsieur, in your attempt to recover it, in order that I may assist you in identifying it."

"And beyond that, you know nothing?"

"Nothing, monsieur."

Duvall began to chew the end of his cigar in vexation. Of all the absurd expeditions, this seemed the most absurd. Presently he turned to Dufrenne and again spoke. "In your repairs upon this snuff box, to which so great a value is apparently attached, did you observe anything about it of a peculiar nature—anything to make its loss a matter of such grave importance?"

"Nothing, monsieur. It is a small, round ivory box, with a carved top, quite plain and of little value—"

"But the contents? What, perhaps, did Monsieur de Grissac carry within it?"

"Snuff, monsieur. It was quite half-full when it came to me, last April. Monsieur de Grissac was in Paris at the time. The spring which actuates the top had become broken—the box is very old, monsieur—and I was required to repair it. That is all I know."

"And you close your shop, and leave Paris without a word, just for a thing like that?"

Dufrenne straightened his bent shoulders, and his eyes sparkled. "When France calls me, monsieur, I have nothing to do but obey."

His reply seemed almost in the nature of a reproof. Duvall made no further comment and relapsed into a brown study. After all, he knew, even in his irritation, that Monsieur Lefevre had not sent him upon this adventure without some real and very good reason. Yet try as he would, he was unable to imagine what this reason could be. Of course, there must have been something inside the box, his final conclusion was, else why should any one have stolen it? No doubt the Ambassador, Monsieur de Grissac, would acquaint him with the truth of the affair. Possibly the box may have contained papers of great value—though why one should choose such a place for the concealment of valuable papers he could not imagine. The whole affair seemed shrouded in mystery, and no amount of speculation on his part, apparently, would throw any light upon it. He lay back in his seat, dozing, and thinking of Grace and their interrupted honeymoon.

At Boulogne they transferred to the boat for Folkstone, and after a quiet passage, found themselves on board the train for London. They reached Charing Cross early in the evening, and taking a cab, drove at once to Monsieur de Grissac's residence in Piccadilly, opposite Green Park.