The Kanaka was fast asleep at his post. Tempest could hardly believe his good fortune. Quietly as a ghost he disappeared back into the sea, and swam to where Jim was waiting. At the far side of the _Nautilus_ he gave his companion a few whispered instructions, and then the pair of them stole to the stern of Flagg’s craft. Inch by inch the two men raised themselves over the side, fearing to awaken the sleeping Kanaka with the slightest oscillation, but so carefully did they work that the boat hardly moved. The sentry was nodding peacefully when Tempest’s hand closed over his mouth like a steel vise, and Jim gripped his legs. The startled sentry instantly began to struggle, but he could only squirm. Tempest had him by the throat, and his fingers tightened. The terrified Kanaka showed no sign of submission. So far there had scarcely been a sound, but it would not have needed much of a scuffle to bring the other two on the scene. Tempest had no intention of choking the sentry. The situation was extremely critical, when Jim wrested the rifle away and gave the victim a blow on the head with the butt end. The sentry collapsed, unconscious, and Tempest stood motionless for a while, listening to see if the sound of the blow had disturbed the others. There was no sign of movement, however, in the little cabin, so the unconscious Kanaka was lowered over the side, and Tempest and Jim towed his form to the beach. Dave appeared out of the shadows and approached them. “You haven’t killed him?” the boy asked anxiously in a whisper. “No. You keep guard over him. Thump him on the head with a rock or something if he gets too lively. We may have our hands quite full enough with the others. Come on, Jim, quick as you like.” While Dave stood on guard over the captive, Tempest and Jim swam off again to the _Firefly_ and regained her deck as silently as before. Flagg’s bunk was in the cabin just forward of the cockpit. An oil lamp was burning, and by its light Tempest could see the form of their arch enemy reclining in his bunk. Within reach of the sleeping man lay a revolver, which glistened in the rays of the lamp. At the far end of the cabin was a door, evidently leading to the place where the other Kanaka was asleep. With Jim at his heels, Tempest took a step forward. CHAPTER XXIII THE SKELETON IN THE SAND Advancing on tiptoes, Tempest stretched out his hand to gain possession of the revolver, and his fingers were almost closing on it when one of the flooring boards creaked. Flagg, who had evidently been slumbering lightly, stirred uneasily. Casting caution to the winds, Tempest reached forward impulsively, bumping against a table as he did so. With a startled exclamation, Flagg half raised himself in his bunk, but by that time the weapon was in the other man’s hand, and the muzzle was pointing straight between Flagg’s eyes.