Peter was climbing into his space suit, an airtight rubberized affair with electric heating grids. This on, he put on his space helmet for the sake of convenience, though he left the little panel of the face window open. Robin slung his own helmet from his shoulder--its vision plate, being homemade, was fixed in place. When they were ready, they went over to the entrance and peeked through the narrow, open space. "Why, it's dark outside!" said Robin. Where before the deep cleft had been lighted by the white light of the outside sun, now it was dark. It was not as dark as the bubble-caverns below had been, for a faint light still penetrated down from the ceiling. They could make out the darker shadows of the surrounding growth, and the Glassies outside were moving figures each illuminated by a small circle of light from their head stalks. "Evidently the sun is going down on the Moon's surface," said Peter. "It was low on the horizon when my rocket arrived. I wonder how cold it will get in this place?" "It seems to be a little colder already," said Robin. "This may bring Von Borck out of his cave to see what's happening." Robin called to Korree, explained what they were about to do. Then while Korree kept a hand on Cheeky, the two Earthlings leaned their shoulders against the big boulder and pushed it aside easily--an effort which would have blocked Moon muscles. Korree had dimmed his headlight and the two men kneeled down and carefully lighted the fuse of their bomb with Robin's flint and steel. The end of the fiber sputtering, Robin took Cheeky and pressed the glass vial into the monkey's paws. "Over there," he whispered to the monkey urgently, and pointed a finger to the darkness opposite the direction in which they would be heading. "Take it over there and leave it," he whispered. He'd often taught Cheeky to fetch and carry, and he hoped the animal would obey. It did. Grabbing the glass tube with its smoking fuse, the monkey dashed off into the darkness. "I hope he remembers to drop it and come back," said Robin. Peter nodded. "Let's get started." The men and Korree started slowly out of the cave. There was a very faint dimness about them, a starlight glow that was just enough to distinguish the presence of objects. They moved slowly, avoiding the telltale lights of passing Glassies. Korree kept his own stalklight dark. Suddenly the peace and darkness were split by a sharp, violent explosion somewhere behind them. Immediately following was a screeching, recognizable as the sound of an angry monkey and almost as frightening.