Larry and Ripon went down the slope of the crater in a series of bounding leaps. The milling Insect-men opened before them, seeming to welcome these unexpected reinforcements. Some of the rebels had already forced the struggling girl to her knees and were lashing her hands behind her back. A solid rank of them faced about with their round shields locked and a tossing fringe of spiked clubs waving atop the metal wall. * * * * * The two Earthlings dove for the shield-wall with their guns flashing. Larry ducked as one of the Insect-men hurled a club which just missed his glass helmet, then pressed the trigger of his ray-gun. The murky beam of the rays stabbed into the shield, melted a hole through it in a fraction of a second, and struck down the man behind. The flashing ray-guns of the two adventurers ripped the shield-wall asunder. A wave of the loyal Insect-men poured in behind them. Larry shifted his ray-gun to his left hand, and snatched up a fallen club with his right. It was heavier than he had expected, a well balanced and efficient weapon. The hard brown shells of the rebels cracked like china under the smashing blows of his Earthly muscles. Then he bounded up on the mound and struck down the pair of rebels who held the girl. Her wrists were now tied behind her. Throwing an arm about the girl's shoulders, Larry hastily faced about. Ripon was a few yards away. A ring of his slain lay around him, but his weapons had been knocked from his hands and he was struggling in the grip of a pair of the Insect-men. A third of the creatures was swinging a club to strike a blow at the scientist's glass helmet. Larry instantly fired, the beam of the ray striking the arm that held the club and shearing it clean off at the shoulder. A viscous yellow liquid dripped out, and the creature dropped writhing on the rock while it clicked in pain. Then Colton and the two quartermasters came charging belatedly up, and the fight was over. The crater was dotted with the still forms of dead Insect-men. Larry noticed that their hard shells gleamed dully in the dim light. The surviving rebels had fled off across the far rim of the crater, and the rest of the throng had gone chasing after them. No one remained in the crater except the strange girl and the party from the _Sky Maid_. When Larry had freed the girl's hands, she turned to the five Earth-men and touched her forehead in a gesture of thanks. Then she stepped across to touch some hidden spring on the far side of the mound, and a trap door opened in what had apparently been solid rock. The girl led the way down a narrow flight of stairs, motioning for the last man down to pull the trap closed behind them.