The Dukases marched on for an hour without saying anything. But during a momentary rest Barbara gripped Ed's arm, thus establishing a firm sonic channel, so that they could talk without using their helmet radios, which might betray them. "I hope we're not too crazy, Ed," she said. "Going out into a wilderness like this, on the basis of a couple of strange notes, and with blind faith that somehow we'll be guided. I hope; I hope!" Her tone was light and courageous, and he was more than ever glad. "Think of our muddled home world, and make that a prayer," Ed said. "We might be doing something to help." So they kept up their march through the night and into the weirdly beautiful dawn. The desert was rusty dun. The sky was deep, hard blue. The dunes were dust-plumed waves, in which a footprint was quickly lost. The rocks were wind-carven spires. Earth was the bluish morning star. It looked very peaceful, denying the need for haste. Its ring was a nebulous blur. Barbara and Ed sucked water into their mouths through the tubes which led back from their helmets to the large canteens in their rucksacks. They swallowed anti-fatigue and food tablets. For a moment they even removed their oxygen helmets. There was no great harm in that; only the distention of blood vessels under swiftly lowered air pressure and an ache and ringing of eardrums, and of course the stinging dryness of the Martian cold against their cheeks. Forty-eight degrees Fahrenheit, below zero, it was just then. "No more clowning," Ed said as they replaced their helmets. "We might get dazed by oxygen starvation and forget what we're doing." They kept up their march, through the morning, past the almost warm Martian noon, and on into the frosty chill that came long before sunset. They were still plodding on when it was dawn once more. In spite of anti-fatigue capsules, they were getting pretty groggy. In his breast pouch Ed had his pen and the envelope on which the latest message from Mitchell Prell had been inked. Now, surely, there had been time enough. So he ventured to disturb the writing materials. There were more words on the envelope: "_True on course--keep moving_." So they continued to follow the pointer of their small gyrocompass, set to stab precisely toward east-southeast. Ed no longer questioned an odd miracle. It was simply there, and he was grateful. An hour later Barbara glimpsed fluttering movement near by: a fleck of bright yellow. Then it was gone behind a large chip of stone. Then it appeared again. Ed saw it, too, for an instant. It fluttered, it chirped plaintively. It was an impossibility in the wastelands of Mars, or anywhere else on the Red Planet, outside of an air-conditioned cage. It was a small, earthly bird. A canary. Barbara stared at it. Her blue eyes were bloodshot and scared. The tired droop of her cheeks deepened. "Darling," she said rather lamely. "I think that fatigue is about to get the better of us." "Think again," Ed said.