Although the pressure was not greatly exerted, an enormous stone, which seemed completely to adhere to the ground, became slowly detached, turned on invisible hinges, and unmasked the entrance of a cave which ran with a gentle incline underground.
This grotto doubtless received air and light through a great number of imperceptible fissures, for it was dry, and perfectly clear.
"Go, López," said one of the strangers.
"Are you going up above?" the other asked.
"Yes; you will join me there in an hour, unless you see me beforehand."
"Good; that is understood."
He then whistled to the horses, which trotted up, and, at a signal from López, entered the cavern without the slightest hesitation.
"Good-bye for the present," said López.
The stranger gave him an affirmative nod; the servant entered in his turn, let the stone fall behind him, and it fitted so exactly into the rock, that there was not the slightest solution of continuity, and it would have been impossible to find the entrance it concealed, even were its existence known, unless one had been acquainted beforehand with its exact position.
The stranger had remained motionless, with his eyes fixed on the surrounding plain, seeking, doubtless, to assure himself that he was really alone, and that he had nothing to fear from indiscreet glances.