He dipped out of sight behind a dune and was gone when they reached the spot. Dunes blocked sight in all directions and a dozen paths branched out between them. "Over there!" Nathan pointed to a fine sand cloud that betrayed the presence of the sled beyond the dunes. Firebird followed and soon they came in sight again. Nathan fired another shot that went wide because of the plunging motion of the sled. Then the enemy suddenly plunged into the depths of an immense blow hole. Firebird swung wide of the hole. Nathan glanced at her in puzzlement. "Where are you going?" "Not down there. It would be fatal to get into a dog fight around the sides of that blow hole. We'll wait for him to come out and hope it is somewhere near us." From the top of a small dune they caught sight of the other sled speeding around the inside of the hole. But he knew he had failed to lure them into it where he would have had as good chance as they. He sped up and over the edge opposite them. Firebird started the sled moving again. Nathan kept his eye on the enemy. Even as he watched the other paused. "He's not running away. He's going to turn and fight!" Firebird held her speed down and let the other build up. He came in shooting. Puffs of flame spurted from the small lance he was firing through the port. Nathan raised the rifle and fired. The shot struck midway between the motor and the cabin and the enemy sled burst into flames. "Good hit!" exclaimed Firebird. Then her face tensed. "He's going to ram us. Get his steering runner." The blazing sled was hurtling towards them at terrific speed now. It was impossible to turn aside so that the enemy could not follow easily. Firebird tried it and the other sled changed to a new collision course. Nathan fired again. Then a shot pierced their own housing as Firebird tried to weave out of the collision course. It made shooting difficult for Nathan but he put another shot into the motor of the enemy. The blazing comet of the enemy sled was less than three hundred feet away now. Firebird could have turned tail to avoid collision, but that was apparently what the enemy wanted. His own position was increasingly desperate with the flames licking about the cabin and threatening the fuel tank. Firebird kept weaving and brought out her own lance. She tried to hit the pilot, but her shots went wild. "Stop weaving," said Nathan. "I've got to get a bead on that runner or we'll have to turn tail." "It'll be your last shot," said Firebird, but she complied. Her slim hands held the sled steadily on a course towards the flaming wreckage that bore down upon them like a meteor. Nathan raised in his seat and aimed carefully. He pressed the trigger. It was a hit. The steering runner of the enemy collapsed. The blazing sled reared end over end into the air hurtling towards them with the force of its momentum. Firebird gave the wheel a mighty jerk and swerved aside as the wreckage plummeted into the space they had just vacated.