The city was feverishly alive with the monsters now. They gathered in groups to stare down at the strange craft, then raced away again, darting in and out of their trap-door homes and streaking here and there across the twisted, tortured granite of the mountainside. The Queen's palace, a vast, raised cocoon of shimmering, silken web, was a veritable bee-hive. Something was brewing! Abruptly the trap-door homes vomited forth monstrous insects by the thousands which spread with prodigious speed along the mountainside. At an unseen signal they poured down upon the plateau and charged the space-ship. The black craft's heavy ray-guns broke into life. Attacking monsters curled up and died as the rays bit into their onrushing ranks. The first wave melted, but an instant later the following waves buried the ship. Insects in the rear darted here and there, dragging away dead and dying spiders. Here was food aplenty! The denizens of the Trap-Door City would live well on their dead for a few days. Abruptly the attack ceased. The crackling ray-guns were still taking toll as the monsters scurried back to the safety of their city, leaving their dead piled high about the hull of the ship. * * * * * Penrun wondered if the monsters would abandon the heaps of their dead. He rather expected that frenzied efforts would be made to retrieve them for food. The problem was solved by those aboard the space-ship, for presently it rose a score of feet in the air and moved a few hundred yards nearer the waterfall that marked the headwaters of the White River. At once a frantic wave of spiders swept down across the plateau scouring it clean of the dead monsters. After that the Trap-Door City seemed deserted. Not a spider could be seen near the shining, circular doors. Only here and there crouched a huge, bristly warrior safe behind a jutting rock with his glittering eight eyes fixed on the motionless black ship below. Again the weary waiting. Penrun could only hope that it would not be long before those aboard the black ship gave him some hint of where the entrance to the Caves might be. Time and again he trained his glasses on the ship only to drop them resignedly. But when noon had passed and the heat of the day was scorching the rock he did not drop his glasses when he looked through them once again. Instead he stood erect in horror and dismay. A girl had dashed out of the air-lock of the ship. She seemed to be familiar. Then he recognized her as the girl who had tried to rob him aboard the _Western Star_. Her face was drawn with agony in the stifling, overpowering heat. She had advanced but a few yards, but she was already staggering uncertainly. What in Heaven's name possessed her to try to venture out in that killing heat? She wasn't even dressed in a space-suit, which would have protected her against heat as well as cold. There was the danger of the monster spiders! Rescue would have to be quick!