Rolf followed the direction of the other's pale blue eyes. Overhead now hung the bottom of the cavern. An almost circular island of pale yellow lifted above the restless dark waters of a vast sea. Rolf realized with a wrench of sudden fear that they actually hung head downward like flies walking across a ceiling. "There," roared Tanner's voice, "is one of the seas of Mars." "One," repeated Rolf slowly. "You mean there are more?" "Dozens of them," the older man's voice throbbed with helpless rage. "Enough to make the face of Mars green again. Cavern after cavern lies beyond this first one, their floors flooded with water." Rolf felt new strength pump into his tired bruised muscles. Here lay the salvation of Earth's thirsting colonies almost within reach. Once he could lead the scientists of North Mars to this treasure trove of water.... "Mark!" The girl's voice was tense. Rolf felt her arm tug at his sleeve and he dropped beside her in the shelter of a clump of coarse-leaved gray bushes. "The Furry Women attack!" * * * * * A hundred paces away Rolf made the dark shapes of armed warriors as they filed downward from the Barrier into the blackened desolation of the desert half of Lomihi. "Enemies?" he whispered to Mark Tanner hoarsely. "Right." The older man was slipping the stout bowstring into its notched recess on the upper end of his long bow. "They cross the Barrier from the fertile plains of Nyd to raid the Hairy People. They take them for slaves." "I must warn them." Altha's lips thinned and her brown-flecked eyes flamed. "The outlaws may capture," warned Tanner. "They have taken over the canyons of Gur and Norpar, remember." "I will take the glider." Altha was on her feet, her body crouched over to take advantage of the sheltering shrubs. She threaded her way swiftly back along a rocky corridor in the face of the Barrier toward the ruins of ancient Aryk. Tanner shrugged his shoulders. "What can I do? Altha has the blood of the Hairy People in her veins. She will warn them even though the outlaws have turned her people against her." Rolf watched the column of barbarically clad warriors file out upon the barren desert and swing to the right along the base of the Barrier. Spear tips and bared swords glinted dully. "They will pass within a few feet!" he hissed. "Right." Tanner's fingers bit into Rolf's arm. "Pray that the wind does not shift, their nostrils are sensitive as those of the weasels they resemble." Rolf's eyes slitted. There was something vaguely unhuman about those gracefully marching figures. He wondered what Tanner had meant by calling them weasels, wondered until they came closer.