Lecoq had refrained from any sign of satisfaction while he was in the jeweler’s presence.  But directly he had left the shop he evinced such delirious joy that the passers-by asked themselves in amazement if he were not mad.  He did not walk, but fairly danced over the stones, gesticulating in the most ridiculous fashion as he addressed this triumphant monologue to the empty air:  “At last,” said he, “this affair emerges from the mystery that has enshrouded it.  At last I reach the veritable actors in the drama, the exalted personages whose existence I had suspected.  Ah!  Gevrol, my illustrious General! you talked about a Russian princess, but you will be obliged to content yourself with a simple marchioness.”

But the vertigo that had seized the young detective gradually disappeared.  His good sense reasserted itself, and, looking calmly at the situation, he felt that he should need all his presence of mind, penetration, and sagacity to bring the expedition to a successful finish.  What course should he pursue, on entering the marchioness’s presence, in order to draw from her a full confession and to obtain full particulars of the murder, as well as the murderer’s name!

“It will be best to threaten her, to frighten her into confession,” he soliloquized.  “If I give her time for reflection, I shall learn nothing.”

He paused in his cogitations, for he had reached the residence of the Marchioness d’Arlange—­a charming mansion with a courtyard in front and garden in the rear.  Before entering, he deemed it advisable to obtain some information concerning the inmates.

“It is here, then,” he murmured, “that I am to find the solution of the enigma!  Here, behind these embroidered curtains, dwells the frightened fugitive of the other night.  What agony of fear must torture her since she has discovered the loss of her earring!”

For more than an hour, standing under a neighbor’s porte cochere, Lecoq remained watching the house.  He would have liked to see the face of any one; but the time passed by and not even a shadow could be detected behind the curtain; not even a servant passed across the courtyard.  At last, losing patience, the young detective determined to make inquiries in the neighborhood, for he could not take a decisive step without obtaining some knowledge of the people he was to encounter.  While wondering where he could obtain the information he required, he perceived, on the opposite side of the street, the keeper of a wine-shop smoking on his doorstep.

At once approaching and pretending that he had forgotten an address, Lecoq politely asked for the house where Marchioness d’Arlange resided.  Without a word, and without condescending to take his pipe from his mouth, the man pointed to the mansion which Lecoq had previously watched.

There was a way, however, to make him more communicative, namely, to enter the shop, call for something to drink, and invite the landlord to drink as well.  This was what Lecoq did, and the sight of two well-filled glasses unbound, as by enchantment, the man’s hitherto silent tongue.  The young detective could not have found a better person to question, for this same individual had been established in the neighborhood for ten years, and enjoyed among the servants of the aristocratic families here residing a certain amount of confidence.