Four years ago, Hirata had walked these same streets as a doshin- patrol officer, the lowest rank of the police force. He’d expected to spend his entire career breaking up brawls and arresting petty criminals, living in cramped barracks, marrying a woman from another doshin family, and raising a son who would inherit the humble station that he’d inherited from his own father. Then chance had brought him and the shogun’s sōsakan-sama together. His loyalty and skill had earned him his current position as Sano’s chief retainer.

Yet his early days at Edo Castle had been plagued by fear of making a mistake and disgracing himself while supervising a hundred other retainers who were mostly older, more experienced, and from better backgrounds than he. The pressure to perform well had kept Hirata in a perpetual state of anxiety, but hard work had brought eventual success and increased confidence. Now he was no longer the diffident, overly serious self upon whom he looked back with amusement. The shogun doted on him; everyone courted his favor; prominent clans vied for the privilege of marrying a daughter to him. As soon as he and Sano finished the investigation into the crimes at the Black Lotus Temple, they would decide which beautiful, wealthy lady would be his wife.

The thought of women provoked a memory that disturbed Hirata’s complacency. What had gotten into Midori today? She’d always been a sweet, lighthearted girl, but now she was acting so strangely. Why did she suddenly want to be a detective? Hirata liked Midori; they’d had good times together, but her foolishness baffled him. While he dismounted outside the high stone walls and ironclad gates of police headquarters, Hirata shook his head. Women! Who could understand them?

Guards bowed to him; a groom took charge of his horse. A doshin, arriving with a trio of civilian assistants and a shackled prisoner, said, “Welcome, Hirata-san,” and let him enter the compound first. As he walked past barracks and stables, former colleagues bowed greetings to him. In the reception room of the main building, square pillars supported a low ceiling hung with unlit paper lanterns. Sun filtered through the open skylights and barred windows into a haze of smoke from the tobacco pipes of citizens gathered around a raised platform. Upon this, four clerks knelt at desks, receiving visitors and dispatching messengers.

“Good afternoon, Hirata-san,” said the middle-aged chief clerk, Uchida. His mobile, comic features stretched in a wide smile. “What can we do for you today?”

Hirata often used police headquarters as a source of information, and Uchida was the central repository for news and gossip. “I need your help in identifying the woman and child from the fire at the Black Lotus Temple,” Hirata said.

“Then you wish to know whether any missing persons have been reported?” Uchida said. At Hirata’s assent, the clerk’s expression turned doleful. “Unfortunately, it’s not easy to trace individuals in this city.”

“I know,” Hirata said. The townspeople belonged to groups of households, each with a headman in charge of recording births, deaths, arrivals, and departures among his group. Officials at Edo Castle monitored daimyo and bakufu households. The huge volume of data was stored at various temples that kept census records. Within the police department, two hundred forty doshin reported incidents in their patrol districts to their supervisors, fifty yoriki who maintained archives at their offices. Thus, the information Hirata sought existed, but wasn’t easily accessible. “That’s why I’m hoping you know something useful.”

“Well, I have heard of a few disappearances.” Uchida’s face arranged itself into an exaggerated frown of concentration. “A sixteen-year-old courtesan escaped from the Yoshiwara pleasure quarter in the spring.”

“She’s too young to be the woman in the fire,” Hirata said. Sano had sent him a message from Edo Morgue, describing the mystery victims.

“A dock worker from Radish Quay came in last month and begged us to find his senile mother, who’d wandered off.”

“Too old.”

“There was a woman who ran away from the Suruga Hill district a few days ago. She’s thirty-four. Her husband is a grocer.”

“That’s a possibility.” After getting the husband’s and wife’s names, Hirata said, “Have any little boys gone missing?”

“One in Kyōbashi.” Hirata’s hopes rose, but then Uchida said, “He’s nine years old.” The child in the cottage had been much younger, according to Dr. Ito. “And the only other missing persons I know of are all men.”

“Oh, well,” Hirata said, undaunted.

He had supreme confidence in himself and his luck, and a bright idea that could save him long hours of perusing dusty archives. He thanked Uchida and walked to a large office at the rear of the building, where twenty clerks sat at desks, preparing memoranda and reports. When Hirata entered the room, they all ceased working and bowed.

“I order you to draft a notice,” Hirata said. He was gratified by the alacrity with which the clerks laid out fresh paper and took up their writing brushes. When he’d been a lowly doshin, these snobbish sons of high officials had begrudged him any attention. “ ‘The shogun’s sōsakan-sama wishes to learn the identities of a woman and child found dead in a fire at the Black Lotus Temple,’ ” he dictated. After reciting Sano’s description of the victims, he continued, “ ‘Persons with information must immediately report it to Edo police headquarters.’ ”

When the clerks finished writing, Hirata said, “Make a thousand copies of that. But first, write this memorandum and send copies to every yoriki: ‘Each doshin shall post the notice on every public notice board and deliver the order to every neighborhood headman in his district.’ ”

Brushes flew as the clerks reproduced the notice. Hirata took a few copies to post along his way to Suruga Hill. As he walked through the reception room, Uchida beckoned to him. “If I may be so bold as to offer some advice?” The chief clerk spoke in a low voice so no one else would hear, his expression grave: “The higher one rises, the farther the distance to fall. By succumbing to pride and ambition, one may end up losing everything that really matters.”

Hirata laughed. “Thank you for the warning, but you needn’t worry about me.”

He left police headquarters with a feeling of accomplishment. If the grocer’s runaway wife was the murdered woman, perhaps he could soon solve the mystery of who had killed her and the other victims and set the fire. If not, he would begin searching the archives. In the meantime, public response to his notices would surely produce some useful information.

And if he had a chance, he would find out why Midori was behaving so strangely.

Police Commander Oyama’s residence was located southeast of Edo Castle in Hatchobori, near the yoriki compound where Sano had lived while serving in the police force. The Hatchobori district was also known for its many carpenters. Sano rode his horse past workshops where the carpenters sawed, pounded, carved, and polished raw wood into doors, rafters, floorboards, pillars, and furniture. Sawdust scintillated like motes of gold in the warm afternoon sunlight. Behind high fences stood the mansions of merchants grown wealthy by supplying timber to a city where fires necessitated regular rebuilding. Up and down the canals floated barges heaped with wood.

Sano stopped at a food stall for a quick meal of fish roasted on bamboo skewers over an open fire, rice, and tea. As he ate, he watched porters carry rice bales, barrels of salt, and dry goods along the quays to warehouses. The reek of the canals mingled with the greasy smoke from cooking. Through the crowds of commoners rode a yoriki clad in elaborate armor, accompanied by an entourage of attendants.