The red head, who had lugged the heavy machine gun all the way with him, patted its snout affectionately. "It plays the devil's tattoo," he said. More fliers materialized in the by now brighter blue of early morning. The sun was just peeping over the serrated tops of the mountains. But still they did not attack. "Afraid of us," Wat chuckled. "Bet they'll send to Mercury for the whole damn army before they come for us." * * * * * The first shock was over. With the inevitable staring them in the face, the men had achieved something of a gay recklessness. Hilary found some natural recessions under overhanging masses of rocks that would afford protection from the searing power of the rays. To be effective, the fliers would have to land in the valley or fly low, thus exposing themselves to the raking fire of the Earthmen's weapons. Hilary posted his little band skilfully underneath these natural shelters in such a way that they would be able to command the bit of sky from every angle. The men jerked and fidgeted. The heavens darkened with massed fliers, and still they came. The Mercutians were taking no chances. "Plenty of guests at our funeral," Wat chuckled, sighting along the barrel of his gun. Hilary left the jesting to the others. He was watching the skies intently. Joan slipped her arm through his. "You see something that we don't. What is it?" He nodded with an intent frown. "There are clouds forming up there. The first I've seen since I came back to this planet. Rain clouds, too, if I know anything about it. Look." Joan tilted her head backward. Thin scuds of vapor darted across the sky, driven by the morning breeze; dissolved and reformed a little farther on. Tenuous wisps, evanescent, wraithlike. The sun shone steadily, unobscured. "Those little things," said Joan unbelievingly. "Why, if that's all you're depending on, we're finished." "Nevertheless they are rain clouds. But _when_ the rain will come is another matter. Very likely too late." Grim came hurriedly over from his post near the entrance to the little valley. His face was placid as ever, but his eyes were worried. "We are being surrounded," he stated calmly. * * * * * Hilary sprang to his feet. "What do you mean?" "Listen. Do you hear it?" Far down the overgrown trail they had followed into the valley came the noise of heavy stumbling feet, innumerable feet. "They are taking no chances," said Grim, his countenance unchanged. Hilary looked swiftly around. The valley was a cul-de-sac, surrounded on three sides of its narrow oblong by precipitous hills. From the fourth side, the Mercutians were coming--an army, from the sound of them. Overhead were a hundred fliers, and more coming. The trap was sprung! Hilary's voice rang out. "All men without guns down the valley to repel invaders. Those with guns remain at your positions; watch the fliers. Wat Tyler in command."