He turned and illustrated the knock on the balustrade of the stairs up which they had hastened.

"We will try it," he added grimly, "on that door when Evasio has had time to go away from it."

They waited a few minutes, and then went out again into the Calle de la Merced. It was the luncheon hour, and they had the street to themselves. They stood for a moment in the doorway through which Mon had passed.

"Listen," said Marcos in a whisper.

It was the sound of an organ coming almost muffled from the back of the empty house, and it seemed to travel through long corridors before reaching them.

"They had," said Sarrion, "so far as I recollect, a large and beautiful chapel in the patio opposite to that great door, which has probably been built up on the inside."

Then he gave the peculiar knock on the door. At a gesture from Marcos he stood back so that he who opened the door would need to open it wide and almost come out into the street to see who had summoned him.

They heard the door opening, and the head that came round the door was that of the tall and powerful friar who had come to the assistance of Francisco de Mogente in the Calle San Gregorio. He drew back at once and tried to close the door, but both father and son threw their weight against it and slowly pressed him back, enabling Marcos at length to get his shoulder in. Both men were somewhat smaller than the friar, but both were quicker to see an advantage and take it.

In a moment the friar abandoned the attempt and ran down the long corridor, into which the light filtered dimly through cobwebs. Marcos gave chase while Sarrion stayed behind to close the door. At the corner of the corridor the friar slipped, and, finding himself out-matched, raised his voice to shout. But the cry was smothered by Marcos, who leapt at him like a cat, and they rolled on the floor together.

The friar was heavier and stronger. He had led a simple and healthy life, his muscles were toughened by his wanderings and the hardships of his calling. At first Marcos was underneath, but as Sarrion hurried up he saw his son come out on the top and heard at the same moment a dull thud. It was the friar's head against the floor, a Guipuzcoan trick of wrestling which usually meant death to its victim, but the friar's thick cloak happened to fall between his head and the hard floor. This alone saved him; for Marcos was a Spaniard and did not care at that moment whether he killed the holy man or not. Indeed Sarrion hastily leant down to hold him back and Marcos rose to his feet with blazing eyes and the blood trickling from a cut lip. The friar would have killed him if he could; for the blood that runs in Southern men is soon heated and the primeval instinct of fight never dies out of the human heart.