“Section C is 1.6 miles and runs parallel to the towpath and the river, between the two. It has a trailhead on the towpath at each end. We could start at the upper one, snowshoe to the lower trailhead, and come back on the towpath.”

“Do you think we could make it over there today?”

“I think so,” Vin said. “The upper trailhead is right off the parkway at a place called Carderock.” He showed her the map, which depicted a recreational field, picnic areas, and a string of parking lots between the canal and the river.

“This all sounds a little premeditated. Like you’ve been planning it for days.”

“Maybe,” Vin said, failing to suppress a smile. “Since I heard the forecast, anyway. A guy at the New Year’s party told me the Carderock trail has a great climbing area for beginners.”

“This doesn’t look like a good day to start your rock-climbing career,” Nicky said. “Besides, I thought you said it was a ‘moderate’ trail.”

“It is. That’s what the map says. I think the climbing rocks are off to the side somewhere. I’m more interested in taking pictures of the woods and the rocks in the snow.”

Nicky’s expression relaxed. She stretched an elbow over her head in a pose that meant she was mentally preparing for exercise.

“C’mon,” he said, convinced now he could persuade her. “When are we going to see conditions like this again here?”

Nicky acquiesced, so they dressed in the shell pants, fleece tops, and hiking boots that comprised their fair-weather snowshoeing gear. Vin packed his camera, a bag of fig bars, and two plastic water bottles in his daypack. He threw their snowshoes and a pair of ski poles for Nicky in the back of his Pathfinder.

The neighborhood streets were still buried under broken snow but the main roads held only a navigable layer of brown slush. A few miles past Potomac they turned off River Road, drove through the tiny enclave of Cabin John next to the canal, and followed the parkway back up along the river to the Carderock exit. The access road entered a culvert that crossed under the canal and the towpath. On the far side the plowing ended, so Vin parked and they got out.

The quiet was striking, with snow-cover canceling the quotidian chorus of background noise. Every sharp exhalation, snap of a plastic clasp, and footstep on squeaky packed snow made a prominent sound. They knelt and strapped on their snowshoes.

“Tastes like real snow!” Vin said, running his tongue over his lips after a dusting of cold powder blew down on him. He noticed a fat bluejay perched on an overhead branch. They extracted Vin’s daypack and Nicky’s poles, then set out toward the parking lots at the end of the access road. Even with the detachable tails deployed on their molded-plastic snowshoes, they sank almost a foot into the unbroken snow with each step. Nicky fell in behind Vin so she could walk in his tracks.

At the end of the uppermost lot they found the sign that marked the trailhead. The trail itself lay buried, but a channel through the woods was marked by blazes of blue paint. Just beyond the trailhead it forked, with the blazes leading leftward up a stepped grade and an unmarked path descending to the right. Vin veered right.

“Hey Magellan. You seem to have lost your compass.”

“From the map back there,” he said, “I think this is the path to the climbing rocks.” He snowshoed downhill through young trees, across a lumpy vein of rocks, and then left around the thumb-knuckle of an emerging rocky fist. The trail traversed a shelf a few feet above the river’s edge. Seen from this angle, the fist was a series of near-vertical rock faces rising forty feet overhead. Vin walked along the base looking up at the cliffs. Snow had collected in the crevices but the faces held only a dusting. The path ended a hundred steps ahead where the fist angled into the river. He took pictures of the rock faces and trees against the snow.

“What do you think? Should we take a climbing lesson here this summer?”

“I guess we could,” Nicky said. Sensing motion above, Vin looked up to see a squirrel scamper across the cliff-top and dislodge a wedge of snow, triggering a miniature avalanche that tumbled into the space between Vin and Nicky. “Or if that’s an omen, maybe we shouldn’t!” They retraced their steps to the fork, then followed the blazes onto the main trail.

As they walked, Vin surveyed the trees ahead of him, looking for the joined sycamores that Kelsey Ainge had mentioned at the party. “Just downstream from Carderock,” she’d said, with those flickering gray-green eyes locking onto his own. Sycamores were plentiful, but he didn’t see any that were joined at the base. He wondered again how she could have known what was in Lee Fisher’s note. And if there was some form of treasure or truth buried beneath the sycamores, why hadn’t she unearthed it herself?

The trail pushed toward the river and undulated along its snowy bank, five to fifteen feet above the water. It was late morning now and Vin grew warm from the exertion of walking through unbroken snow. He stopped to take off his gloves and look back at Nicky. She was ten paces back, stealing glances out at the river, which was studded with snow-capped rocks and little rapids glittering blue in the sunshine. He turned back toward the blazes.

As the trail traversed the sloping, wooded riverbank, they slid down into shallow drainages on their snowshoes, then struggled to ascend the far sides. Vin would climb out first, then take Nicky’s poles and offer her a handhold as she followed. They both removed their scarves and unzipped their jackets. Vin became skeptical that the trail led to a clearing.

And then he noticed a line of indentations along the trail in front of him, like tracks made a day or two ago and covered by a layer of drifting snow. The old tracks descended from a treeless cut up the slope to his left, which had a noticeable lip and blue sky beyond it. The glimpse of sky told him that there was level ground up there, only fifty feet above. There was even an improvised railing made from a two-by-four nailed to two trees near the top of the slope. He waited for Nicky to catch up.

“Can I have a drink of water?” she asked. Vin took off his gloves and daypack and pulled out one of the water bottles. They both removed their hats and drank, and he felt the cold water reinfuse his entire body. They were breathing hard and steam rose from their heads and Vin’s hands. He put the water away and took out his camera.

“I just want to see what's above that little ridge there,” he said. “It looks like some kind of clearing.”

“This wouldn’t have anything to do with 1924, would it? I thought maybe the treasure hunt had petered out.”

“Just a quick look.” He stashed the camera in his pocket, put his gloves back on, and set his snowshoe teeth into the hillside. When he reached the two-by-four railing, he thought he felt stairs beneath the snow underfoot. Driving his hands forward, he crested the ridge.

It was more than a clearing; he stood at the edge of a wide field. To his left was a pavilion with buried picnic tables and barbecue grills. Straight across the field were signs suggesting an adjacent parking lot, and the tracks came from that direction. Feeling sheepish, he realized that this was the recreational field he’d seen on the map, and that the three-quarters of a mile they’d traveled had skirted the string of parking lots and wooded picnic areas that comprised the park.

He stopped to catch his breath, leaning back against the tree that anchored the railing. Looking right he saw that another two-by-four, perpendicular to the first, connected this tree to a third. The connected railings formed an L shape – probably to funnel walkers onto the path he’d ascended, which must be a sanctioned route to the Billy Goat Trail. The Park Service was always trying to steer hikers to designated trails.