"It's in one of the canoes. I'll go and get it," said Frank, and at once set off toward the river bank for that purpose. His path led through a thick grove of bamboos which hid him from the view of the camp after he had traversed a short distance. As he merged on the river bank, whistling softly to himself, the young leader suddenly felt himself pinioned by arms that seemed of enormous strength—though, as the attack had come from behind, he could not see the faces of his assailants. The next minute he was lying flat on his back, bound and helpless with a bit of greasy cloth shoved in his mouth for a gag.
"Keep still, senor, and you shall not be hurt;" said a quiet voice near at hand, and Frank saw bending above him the sallow features of the smiling Portuguese.
"I just have to trouble you for that map I saw you put in your pocket, that is all," went on his captor, while the two huge negroes who had made Frank prisoner stood to one side immovable as carved figures.
"It is lucky for me that you came down to the river bank," grinned the Portuguese as he ran his hand over Frank's clothes, to ascertain the hiding-place of the precious map of the ivory cache, "otherwise I should have had to delay my departure till to-night, and possibly have cut your throat while you slept."
Frank felt as if his heart would burst with rage and mortification as the greasy, smiling Portuguese deliberately drew out the priceless document and gazed at it in triumph. He laid it on the ground beside him while lie resumed his search for other clues.
"That ivory belongs to my master—Muley-Hassan—now," he sneered; "did you think for a minute that we would ever let you white fools get it back again."
It was well for the Portuguese that Frank's hands were not free then. Had they been the dark-skinned traitor would have had a fight on his hands in a few seconds. But suddenly events took a strange turn.
The two blacks uttered a sharp cry of warning as the bushes parted and a huge form dashed out, whirling about its head a glistening axe.
It was Sikaso!
The next minute would have been Diego's last but that his two followers lifted him to his feet and, picking him up like a child, ran for his canoe with him. With a few rapid strokes they were in midstream and paddling up the river with powerful strokes while Sikaso raged impotently on the shore.