IT WAS VERY DIFFERENT, guiding people into the wilderness, Skip was thinking this morning, when it was your own family, instead of a dozen well-paying clients.

He kept thinking of Nusiri's insistence on signs, and the way that condor had been eyeing them, not as if searching for prey, but as if searching for purpose, in the three strangers below. This is my land, he seemed to be saying. What are you doing here?

A question Skip had been asking himself.

And then, there had been that jaguar in the night. And this morning, while fetching his coffee, a brilliant green vine snake, wrapped around a low branch, had turned its pointed, spear-like head his way and followed his every move with those yellow-irised eyes. It gave him the creeps. Signs indeed.

He took a long sip of coffee  and turned his attention to the mountains ahead. Would today be the day they would find Paititi, the City of the Sun, the city of Lost Inca Gold? Or would it be the day Skip or his family finally met their match in one of the most remote reaches of the planet?

Skip shook off the foreboding feeling and turned toward camp. It was time to pack up and get this adventure back on the trail, wherever it might lead them.

Two hours later, Skip was doubting his sanity. Zane had slipped and fallen during a stream crossing, skinning his knee. Nusiri, despite her earlier warnings to the rest of them, had inadvertently brushed up against low-hanging leaves of a manchineel  tree, still wet from a recent shower. She immediately plunged her arm into the river, now narrow and swift-running, to wash off the toxic sap. She, at least, was now no worse for wear. And Skip's left ankle was red and itching with mosquito and tick bites, enough so that he forgot about the still-tender bruise on his right thigh.

The ancient trail through here was for the most part nonexistent, lost to the ravages of the environment and time. Skip wasn't worried about getting lost. From the information he'd gleaned from Jack Fawcett and his journal, he knew to just keep following the river, up to near its headwaters. As for the City of the Sun, he'd been assured that he'd know it when he saw it. So, for now, it was rock-hopping along the river's edge, or bushwhacking through jungle thickets. For the latter, Zane had stepped up and had taken over the machete work. To him, this was his first big adventure in the wild, his chance to prove himself an explorer. Skip was content to let the exuberance of youth break trail. He'd been there, hacked that.

Zane stopped his work for a moment and looked up with an odd expression on his face. Then he waved at something in the trees. Skip was taken aback.

"Who are you waving at?"

"That capuchin monkey up there. He's been following us for the last mile."

"Hmm." Skip glanced all around, wondering what was on the mind of any other animal that might be interested in them. He suddenly remembered an old Hitchcock movie. Considering what man had done to the rainforest since Percy Fawcett's time, it wouldn't be inconceivable for nature to rebel. He thought about that for a second, then shook his head. "Nah," he muttered to himself, and continued on his way.

As the day wore on and  they climbed above five thousand feet, they entered the cloud forest, a world of mist and fog, and a highland jungle like no other, alive with ferns below and epiphytic bromeliads and orchids above, long beards of moss draped from tree branches, and every shade of green imaginable. The trees here were not nearly as tall as in the lowland forests below, but were thicker, with gnarled, twisted trunks, lending an air of dark fantasy to the place. The calls of birds competed with the chatters of monkeys and the myriad chirps, trills, and buzzes of insects. It was a world raw and primeval, not made for man. As a tapir crossed their path ahead, Skip was almost surprised it wasn't a triceratops.

A brilliant orange bird, about a foot tall, with black wings and tail and an odd, disk-shaped crest, landed on a branch even with Nusiri's face, looked her right in the eye, and then flew to a higher perch, keeping watch the whole time.

"Cock of the rock," she said quietly. "He's endemic to this forest."

"It seems to be watching us," said Zane.

"I've noticed. A lot of animals are." She glanced at Skip, letting him know that he wasn't the only one. "I've been thinking about that." She looked as if there was more she had to say, but did not elaborate further. "Come," she said instead. "We best be moving along if we want to make it out of here before dark."

"Place is as spooky as it is beautiful," said Skip, straining to see in the gathering mist. "Sorta gives me the creeps. It's like something out of Tolkien. A tropical version of Mirkwood, maybe."  He fancied he could hear soft footfalls behind him, and glanced over his shoulder. Of course, nobody was there. Just his imagination, playing tricks with the forest.

"Hey, come see this," called Nusiri. She was a few yards ahead, bent down, examining something on the ground.

She had found an area, not far from the river, where the forest litter was thin, exposing an underlying layer of solid, flat stone. What had excited Nusiri was not necessarily the stone surface itself, but the even line between that and the stone next to it, evidence of something man made.

"I think it's the remnants of an ancient roadway," she said. The Incas were expert engineers, who maintained a system of roads along their trade routes throughout their empire, from Ecuador, through Peru and Bolivia, on down to Argentina, with spurs running out to the edges. If the City of the Sun is indeed Paititi, this could be one of the last roads built, to facilitate travel through the forest, down to the lowland rivers below, as they established a new outpost, far from their homeland, Killa's City of the Jaguar.

Skip knelt down to see. As he did so, a flash of motion caught his attention, almost too late.

Thwack!

The arrow that had passed right where his head had been, seconds before, quivered as it lodged itself into the tree trunk next to him. Both Skip and Nusiri looked up to catch a fleeting glimpse of a man, dressed like an ancient Inca warrior, slipping silently into the forest. As one, they scrambled to their feet to give chase.

But the warrior was nowhere in sight. Instead, all they saw was a great bird, a condor, take flight from a tall rock next to the river. An instant later, a hummingbird zipped past their faces and flew off upstream. Then, all was quiet again.

Nusiri looked from the rock, back to the tree with the arrow firmly embedded, back to the rock, and then, to the condor, already almost out of sight, high in the Andean sky. "Apu," she said softly.

"What was that?"

Nusiri hesitated for a second, then explained. "Apu, the shapeshifters." Seeing the incredulous look on Skip's face, she went on. "I didn't want to say anything until I was sure, but I believe our presence here might be attracting the ancient Incan spirits of the mountains known as Apu. They can appear as man or animal, and often come to test the character of people. They protect the mountains, keep the balance between man and nature, and embody the concept of Anyi, the duality of the universe, balance and reciprocity. To the Inca, the mountains themselves were spiritual entities. And that hummingbird, they were thought to be messengers between the spirit world and that of the living."

It was not unlike the beliefs of the Shuar, the culture Nusiri herself had been raised in, Skip could see. Over the years, he had learned to keep an open mind about such things, especially when traveling parts of the world where ancient beliefs still prevailed. It was best to respect such ideas. And each of them had been getting weird vibes from the local fauna. Maybe there was something to it.

"Message received," he said. "I might even take it as a warning. I don't think somebody wants us here. But, we are here now, and at this point, there's not much sense in going back, just because some bird told us to. We just need to have respect and show them, whoever or whatever they are, that we mean no harm."

Zane, meanwhile, had wandered on ahead to just around the bend. "The road continues for a short way," he told them, "to a stone bridge over the river."

They discovered not just one Inca-built stone bridge, but a second, just a short way upstream, where the ancient path crossed back over. The valley had narrowed to a canyon, the river cutting a gorge between two mountains. The roadway, its flat stones still visible here and there, led to the only way through this pass, a trail barely three feet wide, winding its way up and across the steep hillside.

The elevation they had gained in the last several hours was felt in the coolness of the deep shade as they entered the gorge. Crossing the second bridge, a wind that was downright icy cold blew down the river from the Andean heights above. As they began the climb on hewn stone steps, Skip marveled at the masonry workmanship of the tall retaining walls that formed a man-made ledge, creating a passage where nature had never intended man to tread. The walls supported only the path, however, not the travelers who walked its length, for there were no safety walls along the outer edges of the trail, just a thousand feet of mountain air above the whitewater of the river far below. With Skip leading the way, followed closely by Nusiri, and Zane bringing up the rear, they tread with caution, keeping as close to the mountainside as possible.

All day they had been trekking in a generally northward direction. As they rounded the corner of the mountain they found themselves facing east, out from the shadow of the pass, and with the  sun of late afternoon warming their backs. At one point, Skip turned a tight bend in the trail and stopped short, holding up his hand.

"Whoa! Hold up a sec. We've got a section here that might get dicey."

They'd come across a washout, a thirty-foot section of trail that had been eroded away, probably from a storm, or maybe a rockslide. At some time in the past, it had been bridged, by three long logs, each at least a foot thick, laid side by side, spanning the chasm.

"Nothin'  to it," sad Zane. "Just don't look down." He moved as if to test it out with his foot.

"Don't you dare," said Nusiri. "Not after what almost happened on that cliff back at the waterfall."

But Skip was confident, cautiously at least. "We can do this. We just take our time and watch our steps. Don't forget, others have passed this way."

"And how many years ago was that?"

Instead of answering that question, Skip moved into position, his feet finding purchase in the tight V where the logs met. He kept one hand trailing along the rock face of the cliff for balance, and extended the other to Nusiri. She in turn got the idea and held onto Zane's hand behind her.

"Oh," Skip reminded them, "and don't look down."

Together, they inched their way along the makeshift bridge, which proved perfectly sturdy and secure, despite the disconcerting sheer drop below them. It was only thirty feet, after all, not much more than a few strides on the soccer field to Zane, or the distance Nusiri might back the SUV out of the driveway. In short order, they made it across, stopped for a breath and a gulp of water from canteens, and continued  on their way.

The path began to head downward, to meet the upper reaches of the river, now almost a thousand feet in elevation above the stone bridges. Soon, they were walking at river level again, following a twisting canyon on the remnant of the ancient Inca roadway just above the high water mark.

They traveled this way for the better part of another mile. It was getting late in the day, and they were tired and dragging along. "We should think about finding a decent campsite soon," Skip said, as the path went up a small rise and turned a corner.

As they crested the rise, they came to a sudden halt, stunned by the sight before them. There, about a half-mile distant, gleaming like gold in the late afternoon light, stood a magnificent, towering pyramid, obviously of Incan design.

"This is it!" said Zane, all trace of the day's fatigue melting instantly away. "We found it! The City of the Sun. The Lost Golden City of Paititi!"