"Very well, Senor," said Herran, apparently overcoming his reluctance; "that is settled. First, I will be sure he is there. Then, this night, I take you to his house." Una, hearing of this decision, doubted its wisdom. From the few references David had made to his partner in the Guatavita mining venture she had felt instinctively that Raoul was his enemy, an opinion strengthened by the psychometer test used at Stoneleigh. Leighton had agreed in this opinion, more or less; hence Una's surprise that her uncle, who was usually overcautious, should now turn to Raoul for help. "I believe the man knows where David is," he declared. "If he does, he will never tell you," remonstrated Una. "I am not so sure of that." "You may force him to do something fatal," she urged. "On the contrary! By going to him at once I will prevent any foul play--if there is to be any foul play." The possibility alarmed her. The suspense, the mystery surrounding David seemed more than she could bear. Bitterly she remembered Leighton's attitude towards him in Rysdale. And now that their trip to Bogota, insisted on from the first by her uncle, had ended as it had, her faith in him was sadly shaken. She could not accept his judgment in a case about which he had already shown so grave a lack of foresight. Leighton, on his part, realized Una's distrust of him. He did not try to dispel this feeling; but the knowledge that it was there spurred him on to do his best and with the least possible delay. So, that very evening Leighton, piloted by Herran, sought Raoul Arthur's abode on the Calle Mercedes. Like most Bogota houses of the humbler sort, this was a one-storied building, its heavy street door opening upon a wide brick corridor leading to a central patio from which the various rooms were reached. Following Colombian custom, the two men entered without announcement and made their way along the unlighted passage to the main living room, extending from the patio to the street. A lamp at the center of a long table heaped with books and papers distinguished this from the other rooms of the house, all of which were in darkness and apparently uninhabited. A man, somewhat past thirty, his hair slightly grizzled, his features pale and sharpened from study, sat at the table in this main room reading a much-worn leather-bound volume, the large black type and thick, yellowed paper of which gave ample proof of age. Aroused by the noise made by Leighton and Herran, he closed his book with a quick, nervous movement and turned to the doorway where his two visitors stood. "This is Mr. Raoul Arthur?" asked Leighton grimly. "Who are you?" demanded the other, his strange, shifting eyes on the massive figure before him. "My name is Leighton. I am looking for David Meudon." "He is not here," was the quick reply. "I hardly expected to find him here," retorted the savant. "Then why ask me for him?"