“I wouldn’t think that. Not with all the fish to be had in these waters.”

“Maybe the air’s too thick here. We’re not nearly as high as the Guntali near Turput. It wouldn’t matter. The river’s still wide and deep enough to protect us.” She looked thoughtful.

“Something will have to be done about the Na, Etienne. We’ve seen proof that Mai and Tsla can work together, but the Na appear too primitive and combative to be brought into any worldwide interracial process without extensive education and a great deal of care. Just because I’m not fond of them doesn’t mean I want to see the other two dominant races exterminate them.

“They’re not animals. They’re intelligent and have developed a rudimentary society. If you consider the amount of territory they control then a case could be made that they and not the Mai or Tsla are Tslamaina’s dominant life form.”

“I’m glad we don’t have to make the ultimate decisions,” he replied. “Someone else will have to decide whether it’s right to intervene in local affairs to protect the future of the Na, and that’s a long way down the road.”

Though the Skar’s course twisted in a steady curve farther eastward, they continued to travel north toward the planet’s sole ice cap. The occasional appearance of the sun through the uneasy clouds did little to warm them. Despite this Homat spent an inordinate amount of time out on deck, luxuriating in his thermal suit and the freedom it provided, a freedom to laugh at temperatures that would have frozen an unprotected Mai in minutes.

They saw evidence of the ice cap before they set eyes upon it. It announced itself as a brightening ahead, where the ice reflected the sun back against the undersides of scudding clouds. The next morning they lifted on repellers to clear still another rapid, turned a bend in the river, and saw the southernmost edge of the frozen rampart.

The once awesome canyon of the Barshajagad had been reduced to a meandering river valley. Numerous waterfalls tumbled down the melting edge of the cap. They would freeze solid again during the night.

They did not have to trace dozens of the streams to locate the source of the river Skar. The much shrunken but still navigable stream emerged from a huge hole in the wall of ice, having eroded a tunnel a hundred meters high at the entrance. Etienne guided the hydrofoil in until it floated beneath the lip of the vast cavern. Then he carefully nudged the boat ashore, scraping bottom several times before beaching on the gravel.

Overhead the ice had thinned and sunlight poured through the translucent, frozen ceiling, tinting the ice a pale blue and illuminating the river for a distance of several dozen meters from the entrance. Then it was swallowed by cold night. Cold water dripped from smooth icy stalactites, stinging the upturned faces of the crew as it stood on the deck to examine the surroundings.

“What a beautiful place,” Lyra murmured. Somewhere a faint echo concurred with her opinion.

The four Tsla kneeled in a circle, chanting and making signs. The Redowls waited respectfully until the ceremony had concluded before Lyra inquired as to its purpose.

“We give thanks,” Tyl explained. “We feel in our souls a great warmth, as must thee, for thy journey has been far longer than ours.”

“We couldn’t have made it without your help,” Etienne told him, “and without the aid of your people.”

“All given freely in the pursuit of knowledge. We were glad we could help.” Swd and Yij likewise expressed their feelings, while Yulour stood nearby and looked on with bemused contentment.

“What do we do now?” Homat inquired, peering out through the eyeslits in the cloth that covered his face. “Do we begin our return tomorrow? A long journey.”

“I know you’re anxious to go home, Homat, but we’ve come all this way to see the source of the Skar and we’re not leaving until we do so.”

Homat sounded puzzled. “But have done so, de-Etienne.” He gestured at the spacious cavern and the distant darkness. “What other source can there be?”

Etienne smiled as he turned to point into the blackness beneath the ice. “This isn’t the river’s source. Somewhere back there it emerges from the mass of the ice cap, probably in the form of a hot spring. I can’t think of another mechanism which could have bored so deep a cave in the body of the ice. I need to record it.”

Homat’s eyes grew wide. “You can’t mean to go back in there, de-Etienne! This is the top of the world. Who knows what devils and monsters lie in wait for us in the night which lives throughout the day?”

“Why should any lie in wait,” Lyra asked gently, “since no one ever comes here? If any did live back in there they’d long since have given up hope of any meals coming to visit them.”

“You argue very plausibly, de-Lyra. My mind wishes to believe you, but my insides are not convinced.”

“If you’d feel safer you can camp on the shore here and wait for us to return. I doubt the river runs very far back, hot springs or not.”

“No, no, I will come with you,” the Mai insisted bravely. “I would rather do that than stay here alone. You are certain there is not far to go?”

“I can’t be sure, but I’d be willing to bet we’ll have less than an hour’s journey in the boat. If the water becomes too shallow, we’ll travel the rest of the way in on repellers.”

“Why do your words not make me feel confident, de-Etienne?”

“Relax, Homat.” He turned to Lyra. “When we reach the source I want to take some core samples. This must be very old ice and the geologic history of the planet is stored here, conveniently waiting to be thawed out for study.”

Lyra offered no objection. Their goal was within reach. Soon they would begin the long journey back to warmer climes. Let Etienne enjoy his fieldwork for a day or two. There was no reason to rush now that they’d arrived at their intended and eventual destination.

He looked to his right, deeper into the cavern. “There’s a nice wide spot. I’m tired of rocking. The water there is gentle and shallow. I’ll move us over and set the foils down on the gravel. Be nice to sleep without rocking for a change.”

“Second the motion,” Lyra said. “It should be safe enough. There’s no sign of carnivores about, no bones or dung on the beach, and the water should keep any small vermin clear of the boat, assuming this environment is benign enough to permit their existence.”

“I’ll run a good charge through the hull. That ought to keep off any late-night visitors.”

“It would be delighted to sleep so quietly,” Tyl agreed.

“Then it’s settled. We owe ourselves the rest,” Etienne declared. “First thing tomorrow morning we’ll go Upriver to the source so I can get my samples. With luck this ice may predate the collision that created the Groalamasan. That will give me plenty to do on the way back Downriver.”

“You did enough griping about the heat down south to fill a book, and now you can’t wait to get back to it,” Lyra chided.

“I’ve always been cold-natured, Lyra, you know that. It doesn’t mean I enjoy sweating down to skin and bones, though.” For a change the argument was friendly. In its own way that was as great an accomplishment for the two of them as was reaching the head of the Skar.

Lyra was sound asleep when the muffled scream woke her. She blinked as her head lifted from the pillow and she stared across the cabin. Soft green lights from ship’s instrumentation lit the darkness. A soft wheeze alongside indicated that her husband still slept.

The scream had barely faded and she was beginning to wonder if she’d dreamed it when suddenly a cluster of the green lights changed to red and a warning horn started to blare. Etienne woke instantly, slid off the bed and struggled with his pants.

“False alarm?”

“I don’t know,” she told him, still straining to hear. “I thought I heard something yell.” The horn continued its racket as a soft knocking sounded at the door. Lyra opened it as she fought with the seals of her blouse.

“What is happening?” Tyl asked sleepily. The remaining Tsla clustered in the corridor behind him. “There are strange noises outside and Swd thinks he smells something even though we know we are protected from the air outside.”

“Noises and smells and you think you heard something,” Etienne muttered as he sealed his coat. “That settles it.” He pushed past Tyl on his way to the cockpit.

The light of three of Tslamaina’s four moons poured through the transparent plexalloy. The horn continued to shout as Etienne strained to check the instruments. “Don’t see anything outside. No abnormal readings. We haven’t moved from where I parked us yesterday evening and the hull’s still electrified.”

“I’ll check astern,” Lyra told him. She removed her pistol from its charging slot.

“Watch yourself,” Etienne admonished her.

With the Tsla following curiously she worked her way aft. There was no sign of Homat, but that didn’t worry her. Anything less than a complete upset of the boat would not be enough to pry him from the comfort of his overheated cubicle.

Cautiously she cracked the stern doorway. Freezing air brought her all the way awake. The rumble and gurgle of the shallow river was the only sound as she stepped out onto the rear deck.

A glance forward showed only darkness. There was no movement in the upper reaches of the cavern. Outside only the moons moved in patient procession against the sky. Something shorted out, she thought, wondering if some other strange local critter was somehow playing havoc with their instrumentation.

A heavy weight landed on her right shoulder. She went down hard. The asynapt went flying across the deck. A big chunk of dead log lay next to her.

The Na who had thrown it now peered over the gunwale, eyes glittering in the moonlight. Several similar hairy faces joined the first. One huge, muscular arm reached over the top of the railing and Yij disappeared over the side.

Tyl and Yulour took Lyra under the arms and hauled her toward the doorway. A second club flew toward them. It landed short, booming across the metal deck.