After about three hours they turned into a smooth and level road. It wound up and down over the rolling rocky plain, evidently a highway of great age. Occasionally they passed crumbling ruins beside it. Larry supposed that the road and the ruins dated back to those very ancient days before the Lunarians withdrew their shrinking supply of air within the Great Barrier. Now that the road was smooth, the Insect-men pulled the carts along at a whizzing pace. The light wheels whirred as the wagons shot ahead. The scene, Larry reflected, was like a nightmare. All about him were the chill mountains and craters of the Moon, lifting their jagged peaks against the cold stars. Ahead of the speeding wagon ran the toiling cluster of Insect-men, their hard shells gleaming faintly in the starlight and their glowing antennae bobbing in a swift rhythm as they ran. The treads of the wheels rattled on the rocky surface of the road, the horny feet of the Insect-men made a steady scraping sound as they ran. The two men seated in the cart ahead were monstrous and misshapen figures in their space suits. Larry's companion had remained sullenly silent, in spite of several efforts to start a conversation. This was unusual in one of the normally pleasant and talkative Lunarians, but Larry had not thought much about it. Now, as he made some remark about the speed of their progress, he heard a low chuckle and in his earphones sounded the voice of Diana Staunton. "Yes, Larry, we travel fast. In a few days we will enter the zone of sunlight." "_You_," he exclaimed. "This expedition is too dangerous. I would never have let you come if I had known." "Why else do you think I kept so silent until now, when it is too late to send me back?" she asked, and though he could not see her face through the glass of her helmet in the darkness he could tell that she was smiling. "Neither would Pyatt of Kagan or my father have let me come. I stole the space suit of the young man who was to accompany you and left him locked in a storeroom." "You will have to remain outside when we go within the barrier." "Where you go, I go," she said with finality. * * * * * Sunrise on the Moon! There was no sudden onslaught of light as on the Earth, for the Moon day was twenty-eight days long! Yet, as they progressed steadily toward the horizon, the Moon's rotation brought the edge of the sun gradually into sight above the barren horizon, and as the days passed, a blinding glare of light swept in upon them and they moved the dark glasses into place in front of the windows of their space-suit helmets. The temperature rose rapidly with the coming of the two weeks' sunlight, and before long the frost on the space suits was melting. Then, stretching along the crest of a mighty mountain range ahead, Larry saw a lofty gray wall that went so high its top was almost lost from view above. They had come within sight of the Great Barrier!