"Can't breathe!" Chastain retched, exhaling words from empty lungs. "Can't bre—!" Chastain's groping hands found his mask; he pulled it over his face, wild eyes narrowing to slits. He attempted to sit up, but a stab of pain shot through his body— Chastain stiffened and fell supine, holding his mask to his face with both hands, desperately, as a drowning man with a life preserver.

MacArthur reached to remove his own mask. No sooner had he broken the face seal than was he stricken with an acrid pungency, an odor beyond description and magnitude. Tears welled, and sharp pain penetrated nostrils and sinuses. He fell to a knee, trying to expel the painful sensation from his nose and lungs. Slamming his breathing apparatus back to his face, he dared to breathe. Nausea surged through him. Fighting panic, he sucked in a lungful of oxygen.

MacArthur' s breathing passages slowly cleared, but a sour, metallic taste clung to his palate. MacArthur looked at Chastain; both men were frightened. Their only communication alternative, beside sign language, was the radio. MacArthur broke regs and activated his transmitter.

"Air's no good. Big trouble, Jocko," MacArthur gasped, looking around, checking the slowly moving herd. The buffalo had calmed and were grazing on the spongy, dung-spotted turf. A few had moved closer, although none approached closer than an hundred meters. The motley, red-brown beasts were massive, as tall at the shoulder as a man, with fur-shrouded fat humps similar to prehistory mastodons or musk oxen. Mature animals carried a stubby but sharply hooked rack of black horn.

MacArthur stood erect and looked down at Chastain. The big man was pale and wide-eyed, still suffering from his dose of atmosphere. "Where' you hurt, Jocko?" MacArthur asked.

Chastain closed his eyes, his breathing rapid. His hand activated his transmitter. "My back. Multiple retro—hit like a ton of bricks. Must of blacked out. What we going to do, Mac?"

MacArthur, still dizzy, tried to think. Their breathing systems would supply oxygen for two to four hours at the most, probably closer to two hours considering the stress. "Let's move. Can you walk?" he asked, fearing the worst.

"Don't know," Chastain responded. The big man rolled onto his knees. Between the two of them they were able to hoist Chastain erect, but only barely. Hunchbacked, listing heavily to his right side, Chastain staggered down the decline, struggling to lift his feet from the indentions caused by his ponderous weight.

MacArthur shouldered his pack and gathered the fluttering parafoils. An idea formulated. MacArthur removed his pack and attached it to Chastain' s, arranging the turtle packs in tandem. He secured both parafoils to the assembled mass and gingerly redeployed the foils in the freshening wind. To the skittish dismay of the buffalo, the parafoils billowed opened and jolted their load over the uneven terrain. Using harness webbing for a lanyard, MacArthur followed the wind-powered sled, breaking into a trot to keep pace. MacArthur quickly caught up with his crippled cohort.

"How you doing, Jocko?" MacArthur asked over the UHF, as he pulled abreast, holding the jerking cargo back against the insistent winds.

"Not sure I can, Mac," Chastain gasped, his sweaty face ashen.

"Yes, you can, Jocko. If I loose sight of you, I'll wait." Chastain nodded and MacArthur pulled ahead. Despite his words, MacArthur was worried. How could they escape what they could not see?

The terrain transformed as they descended. Crystalline escarpments spotted with livid lichens protruded from the taiga, the footing firmed, and the ground lost its sponginess. As MacArthur topped a small rise, he spotted a line of scraggly, yellow-trunked trees. Beyond the trees, the valley expanded and descended steeply into the haze. MacArthur knew the valley ended at the great river, but he also knew the lower they descended, the higher they eventually would have to climb.

"You'll see some trees in the distance, to the right. I'm heading for them. We'll check out the air when we get there. Keep it in gear, Marine!" MacArthur exhorted over the radio, trying to reassure himself, as well as to keep Chastain moving. He clattered ahead, moving at a jerky lope, the hard shells of the turtle packs careening off rock. The wind abated, no longer carrying the urgent power evident on the higher terrain. MacArthur had to pull the equipment through swales and over gentle ridges. After an hour, sweat-soaked and exhausted, he gained the wind-bent trees espied from the top of the valley and sat heavily on one of the many quartz-veined boulders jumbling the area. He rested head and arms on trembling knees; a gnarled and twisted tree, its rough, mustard-colored trunk and spiky green-gray needles provided an oasis of cold shade.

It felt exquisite to rest, but survival fears held sway. Insulated by his helmet, MacArthur could hear only the pounding of his heart and the rasping of his lungs. He lifted his head and checked the thin stand of trees. Five paces distant a clear spring gushed from a flower-shrouded seep, forming an energetic rivulet that bubbled out of sight over granite steps. The water triggered a desperate thirst.

MacArthur fatalistically inhaled a full breath of oxygen and fingered the fitting on his mask. Loosening his helmet, he let the mask drop from his face. An insistent current of chill air caressed his sweaty cheeks. He pulled off his helmet. His hearing was assaulted by the persistent symphony of nature. A brittle breeze swept over his exposed neck and brow. Still holding his breath, he shivered.

Positioning his mask near his face, MacArthur partially exhaled and then cautiously sniffed the air. It smelled horrible: an offending stench of incredible magnitude—terrible odors, a bitter conglomeration of offal, carrion, sewage, and burning chemicals so persistent and penetrating that all senses were assailed and dulled. His body begged to collapse into some minimal essence, to sleep, to escape. His head ached. His eyes watered, but somehow he knew that it was not fatal. He could breathe; his lungs could process the atmosphere. He could breathe without the involuntary spasmodic rejection experienced in the landing zone. It was horrible, but it was air, and the prospect of running out of oxygen lost its urgency, if not its fear.

He looked down at the clear spring at his feet. Water, yes. It had to be. What did it matter that the air was breathable, if the water was undrinkable. Without water they would die, too. They were marooned.

Casting helmet and mask aside, MacArthur fell to his knees. He sniffed at the pulsing fluid, smelling only the horrid air. He sipped at the water, trying to sample it, but thirst trampled caution, and he drank noisily of the sweet liquid.

The gods of the sky were angry, and Brappa bore witness to their displeasure. Brappa and the other sentries had seen flyers descending from the heavens. They had not been drunk on thickweed. There had been thunder in the morning skies and star bursts to the east. Not lightning but bright blossoms of red and yellow—in a sky devoid of clouds! After the brilliant lights came more terrible noises, more thunder! So loud, his ears rang. And from out of the bright fires and noise came four flyers, high overhead in the cold, liftless morning skies, flying toward the lakes.

Brappa, son-of-Braan, lead sentry of the morning watch, danced nimbly down the precipitous granite face. The golden glow of dawn overflowed into the river valley, illuminating and melting the thin crust of frost decorating the upper rim. The sentry chased the sunrise down the chasm's walls, jumping lightly into the air every few steps, spreading diaphanous membranes and gliding softly to a next landing, there to run three or four landbound steps and jump and glide again. His leaps covered many spans. He could have soared the entire descent, but he needed time to think.