Echo is naturally magnetic, probably more so than any other planetoid—and Neal Bormon cursed softly, just to relieve his feelings, as that magnetism gripped the small iron plates on the soles of the rough boots with which the Martians had provided him. Slavery—and in the twenty-ninth century! It was difficult to conceive of it, but it was all too painfully true. His hands, inside their air-tight gauntlets, wadded into fists; little knots of muscle bulged along his lean jaw, and he stared at the