"No one knows," she answered. "That is why I live always on the brink of a volcano. Many people are searching for them. No one as yet has succeeded. But that may come at any moment."
"Madame," he said, "can you tell me who killed these men?"
She raised her eyebrows.
"I cannot," she answered coldly.
"Madame," he declared, "the man Barnes was a pitiful blackmailing little Jew! For all I know, he deserved death a dozen times over—ay, and Bentham too! But the law does not look upon it like that. Whoever killed these men will assuredly be hanged if they are caught. Don't you think that your friends are a little too zealous?"
She met his gaze unflinchingly.
"If friends of mine have done these things," she said, "they are at least unknown to me!"
He drew a short choking breath of relief. Yet even now the mystery was deeper than ever! He began to think out loud.
"A friend of yours it must have been," he declared. "Barnes was murdered when in a few hours he would have parted with those letters to your enemies; Bentham was murdered when he was on the point of discovering them! There is some one working for you, guarding you, who desires to remain unknown. I wonder!"
He stopped short. A sudden illumining idea flashed through his mind. He looked at Madame de Melbain fixedly.