Monsieur Thomery had just appeared at the top of the grand staircase, accompanied by a gentleman, whose simple black coat was in striking contrast to the light dresses and brilliant uniforms of the guests.

Someone whispered:

“Monsieur Havard!”

It was, in fact, the chief of the detective police force.

Within a couple of minutes of his frightful discovery, Thomery had rushed to the telephone and had called up Police Headquarters. It was a piece of unexpected good fortune to find Monsieur Havard there at so advanced an hour. He had immediately responded to the call in person.

Whilst crossing the reception rooms Thomery talked to him in a low voice:

“Accept my grateful thanks, Monsieur, for having answered my appeal for help so quickly. No sooner did I discover the body of my Princess than I lost no time in having all the exits from the premises watched.

Unfortunately I was obliged to leave my reception rooms for quite a quarter of an hour, so that I cannot tell you what happened there. If only I had been able to remain with my guests, I might possibly have surprised some movement, some gesture, some look, which would have put me on the track of this murderous thief... unfortunately...” Monsieur Havard interrupted, smiling:

“That does not matter, Monsieur: if the guilty person is among your guests and has in some way betrayed himself, I shall hear of it. There are, at least, four or five plain clothes men among the dancers, I can assure you of that.”

“I can assure you to the contrary!” replied Thomery – “I know my guests – know who have been admitted here.”

“I also am sure of what I say,” insisted Monsieur Havard. “There is scarcely a ball, a reception, however select it may be, where you will not find a certain number of our men.”

Thomery made no reply to this: they had arrived at the door of the fatal room. The doctor was standing beside the victim. Dr. Marvier reassured Monsieur Havard. He announced that the Princess had been almost literally felled to the ground by a most powerful soporific, but was in no real danger : she would certainly regain consciousness in the course of an hour or two.

But she must be kept perfectly quiet: that was absolutely necessary.

Monsieur Havard did not question the doctor’s statement. After a rapid glance he was able to form his own opinion. There had been no struggle : the victim’s wounds were due to the haste with which the thief had torn the jewels from Sonia Danidoff’s neck. He next considered the two windows which, with the door opening on to the gallery, were the only means of entrance and exit the room had.