“Aoi saw the killer pass piles of wood and canals with logs floating in them,” he explained.

Hirata nodded. “The Honjo lumberyards.”

The road ended at the Tatekawa River, a small tributary of the Sumida. In the lumberyards lining its banks, laborers cut and planed timbers, and stacked finished boards on barges bound for the city. The clear morning air rang with men’s shouts and the rasp of saws and scrapers. Sunlight filtered through a golden haze of sawdust that bore the winy scent of freshly cut wood. A network of canals branched off the Tatekawa River, all choked with logs transported from the eastern forests. Burly men walked along the logs as easily as on land, guiding them with poles.

While Hirata stood watch for assailants, Sano asked the lumbermen if they knew of an abandoned house in the marshes, at the intersection of two canals, that somehow resembled a samurai’s helmet.

“Nothing like that on our route,” said the foreman of a log transport team.

“No. But then, I don’t go out in the marshes much.” This answer came from woodworkers, porters, and sweepers.

Giving up, Sano said to Hirata, “If the killer travels often between the house and the city, at least it can’t be far.”

Beyond the lumberyards lay open marshland, through which they headed east on a narrow road bordered by lilies, ginger, ginseng, and other spring flowers. The high blue sky reflected in standing pools that broke the expanses of lush green grasses. Willows drooped graceful boughs hazy with spring foliage. As humans grew scarce, wildlife abounded. Geese honked and gulls screeched overhead. Fish jumped in ponds, where water rats prowled, turtles sunned themselves, and white cranes fed on frogs and water insects. Butterflies flitted through the air; bees droned. Although the stinging flies and mosquitoes wouldn’t swarm in full force for some months yet, the weather was as balmy as summer.

Spaced at wide intervals along the road, tiny shacks stood on stilts above the marshes. Sano stopped at one.

“We’ll ask for directions,” he told Hirata.

The marsh people eked out a meager living by collecting fish, shellfish, eels, frogs, and wild herbs to sell in the city. They would, out of necessity, range farther into the marshes than the lumbermen. In response to Sano’s call, a weathered brown woman dressed in faded cotton kimono and headcloth came to the door. When asked about the house, she said, “I’ve heard about a hunting lodge that a rich samurai built a long time ago and doesn’t use anymore. I’ve never seen it myself, but I think it’s that way.” She waved a hand in a vague gesture to the northeast.

Raising a hand to shield his eyes from the sun, Sano squinted into the distance, but saw only more marshes. “How far?”

“Oh, a few hours’ walk.”

Encouraged, Sano led Hirata off the main road and onto a narrow northeast-bound branch. This trail meandered, veered, and repeatedly doubled back on itself. The sun climbed higher in the sky. Noon came and went, and still they did not find the abandoned house. They passed no other travelers, and no other shacks where they could ask for directions. Sano grew increasingly worried. Would they reach their destination by the hour of the dog, when Aoi had said the killer would arrive?

“The house is out here somewhere,” he said, as much to reassure himself as Hirata. “We should find it soon.”

Doubt shadowed the young doshin’s eyes, but he neither questioned nor complained. Sano was grateful for his tact. Grim and determined, they pushed on.

All too soon, the day began its inevitable decline. The sun dropped lower in the west. The fleecy white clouds turned first pink, then violet against a flame-orange sky. The grasses darkened to murky gray. Waterfowl ceased flight to clamor beside the ponds. Every tree held a twittering orchestra of birds. The air grew chill; a thin vapor that smelled of fish and rotting vegetation rose from the marshes. Soon it would be too dark to search anymore. Less than three hours remained before the killer’s expected arrival at the house.

Then Sano spied a building in the distance to the north. “There!” He pointed. “Look!

With no time to waste on looking for a road to the house, they dismounted and plunged into the marsh, leading their horses. The shoulder-high grasses closed around them. Icy water soaked them to the knees; mud sucked at the horses’ hooves. Small creatures fled at their approach. Striking a straight line toward their target soon proved impossible. Deep pools and impenetrable reed thickets constantly forced them to detour. Keeping the house in view grew increasingly difficult as the darkness deepened. Only one thought consoled Sano: following them secretly would be impossible for an assassin. At last, after an hour’s tedious trudge, they emerged on solid ground, at the junction where two shallow, weed-choked ditches merged to form a wider one that meandered off into the distance. Perhaps two hundred paces beyond the junction rose the structure they’d seen.

“Come on,” Sano said, freshly energetic in his eagerness.

He jumped a ditch and urged his horse across it. Leaving Hirata to follow, he mounted and rode the remaining distance. The ground, though as overgrown with grasses as the surrounding terrain, was higher and firmer here. As he neared the house, its features grew apparent.

The house was a minka, the sort of dwelling found throughout rural Japan. A crumbling earthen wall surrounded it, also enclosing a ruined barn. The house had three stories counting the attic, with a few tiny barred windows set into half-timbered, unplastered mud walls. Sano dismounted outside a gap in the wall where rough wooden pillars marked the place where a gate had once hung. He drew and expelled a long breath of recognition.

“See the roof,” he said to Hirata, who’d caught up with him. “Doesn’t it look like a samurai’s helmet?”

Made of thick, shaggy thatch, the roof jutted out between the first and second levels in wings that resembled the side flaps on a warrior’s helmet. From the second story, it ascended to a flat portion over the attic before tapering to a narrow point. Exposed beams on either side of the ridgepole crisscrossed, forming long projections like horns crowning a general’s headgear. But the place looked deserted, with an aura of complete abandonment. Sano’s inner sense told him that no one had made consistent use of the house in ages. He felt a momentary prick of doubt, which he dismissed.

Hirata cleared his throat and said, “Sumimasen. Forgive my forwardness in speaking, sōsakan-sama. If the killer owns the house, the property records might tell us who he is.”

Sano regarded his assistant with new respect. He’d guessed that the killer had simply taken over the old house, but Hirata’s alternative made sense.

“That’s a good idea,” he said. “If we don’t catch him tonight, we’ll check the records when we get back to town.” But he fervently hoped that they would, and that a long search wouldn’t be necessary. “Now let’s look around.”

Tethering their horses inside the wall, they circled the property. At the house’s rear, an overgrown trail ran west, probably to link up with a road leading toward the city. It bore no visible foot- or hoofprints or any other signs of travel. Around them, as far as Sano could see, stretched the marshes: a vast level spread of land, accented by occasional trees. The only sound was the wind rustling through the grasses.

“Let’s go inside,” Sano said, swallowing his misgivings.

From their saddlebags, they fetched candles and matches, then crossed a jagged flagstone path through an earthen courtyard that sprouted knee-high grass as the marshes slowly reclaimed it. The front door was unlocked, but the wooden planks had swollen in the damp climate, and opening it took their combined strength. Lighting their candles, they cautiously stepped inside the house.