“Who is it?”

“Monsieur, it is no one.”

The Spain’s voice was dry and soft.

“What is it?”

“Monsieur, it is the desert drum. There will be death in Sidi-Massarli to-night.”

I felt myself turn cold. He spoke with such conviction. The murderer was still smiling, and I noticed that the tired look had left him. He stood in an alert attitude, and the sweat had dried on his broad forehead.

“The desert drum?” I repeated.

“Monsieur has not heard of it?”

“Yes, I have heard—but—it can’t be. There must have been someone.”

I looked at the white teeth of the murderer, white as the saltpetre which makes winter in the desert.