Wethermill snatched his hands away from before his face.

"We talk theories," he cried desperately, "of what may have happened at the villa. But we are not by one inch nearer to the man and woman who committed the crime. It is for them we have to search."

"Yes; but except by asking ourselves questions, how shall we find them, M. Wethermill?" said Hanaud. "Take the man! We know nothing of him. He has left no trace. Look at this town of Aix, where people come and go like a crowd about the baccarat-table! He may be at Marseilles today. He may be in this very room where we are taking our luncheon. How shall we find him?"

Wethermill nodded his head in a despairing assent.

"I know. But it is so hard to sit still and do nothing," he cried.

"Yes, but we are not sitting still," said Hanaud; and Wethermill looked up with a sudden interest. "All the time that we have been lunching here the intelligent Perrichet has been making inquiries. Mme. Dauvray and Mlle. Celie left the Villa Rose at five, and returned on foot soon after nine with the strange woman. And there I see Perrichet himself waiting to be summoned."

Hanaud beckoned towards the sergent-de-ville.

"Perrichet will make an excellent detective," he said; "for he looks more bovine and foolish in plain clothes than he does in uniform."

Perrichet advanced in his mufti to the table.

"Speak, my friend," said Hanaud.