The second group, identical to the first, left by a side gate. More troops escorted another Sano toward the Nihonbashi merchant quarter.

The third group consisted of three low-rank soldiers dressed in cotton kimonos, leather armor tunics bearing the Tokugawa triple-hollyhock-leaf crest, and plain helmets. They rode out the servants’ gate. While the first two groups went their conspicuous ways, the real Sano traveled incognito with Detectives Marume and Fukida. The decoys drew attention away from their secret journey.

Meanwhile, Hirata rode accompanied by his troops toward Kannei Temple. They escorted four bearers carrying a litter. On it sat the trunk in which the skeleton of Tokugawa Tadatoshi had traveled from its grave. At the same time, two porters clad in loincloths and headbands carried a barrel in the opposite direction.

The porters trudged through the Kodemmacho slum. The wind swept debris along the twisting roads and whipped the smoke from outdoor hearths and beggars’ bonfires outside miserable hovels. The setting sun reflected pink in open, reeking gutters. The porters skirted garbage dumps and plodded across the ramshackle wooden bridge over a canal that served as a moat for Edo Jail, a dingy fortress whose gabled rooftops lurked behind high, moss-covered walls studded with watch turrets. At the ironclad gates, the porters called to the sentries in the guardhouse: “Delivery for Dr. Ito.”

Shortly after the porters entered the jail with the barrel, Sano, Marume, and Fukida arrived, confident that nobody had followed them from Edo Castle. Any spies monitoring Sano’s comings and goings must have followed one or the other of his impersonators. When he and his men reached the gate sentries, the brawny, jovial Detective Marume said, “Let us in.”

The sentries saw the Tokugawa crests on their garments and obeyed, no questions asked. Sano’s group proceeded through the prison compound, unrecognized and unchecked by guards. They dismounted in a courtyard enclosed by a bamboo fence. There stood a low building with flaking plaster walls, barred windows, and a raggedy thatched roof: Edo Morgue, where the victims of floods, fires, earthquakes, and crimes were taken. The porters-men from Hirata’s detective corps-sat on the ground near the barrel, which they’d laid at the feet of Dr. Ito.

With his plentiful white hair and tall, upright figure, dressed in the traditional dark blue coat of a physician, Dr. Ito looked no different than when Sano had last seen him almost five years ago, even though he must be over eighty now. When he saw Sano, surprise and pleasure transformed his stern face.

“Sano-san! Was it you who sent me this gift?”

They exchanged bows, and Sano said, “Yes. I’ve come to beg your expert advice.”

Once a renowned physician, Dr. Ito had lost his profession, his family, his place in society, and his liberty after he’d been caught smuggling scientific knowledge from Dutch traders and performing medical experiments. The usual punishment for those offenses was exile, but Dr. Ito had received a life sentence as custodian of Edo Morgue.

“In regards to an investigation?” Dr. Ito asked. When Sano assented, he said, “I’m delighted. It’s been a long time since the last one.” Sano had solved other cases in the past several years, but none requiring Dr. Ito’s aid. “It’s also been too long since we’ve met.”

“I regret that,” Sano said.

Coming to Edo Morgue was a risk Sano couldn’t afford except under special circumstances. Associating with a criminal could cost him his good name, his allies, and the shogun’s favor. In addition, what happened here during his visits involved foreign science. Should Sano’s collaboration in it become public, he would suffer far worse punishment than Dr. Ito had. Sano had much farther to fall.

“You’ve endangered yourself by coming here today,” Dr. Ito said with concern.

“I’ve taken precautions.” Besides employing a disguise and decoys, Sano had covered the trail he’d left in the past. Years ago he’d paid the gate sentries to keep quiet about his and his staff’s clandestine visits. Later he’d transferred those men to other, faraway posts. His disguise had fooled their replacements. Now only Dr. Ito and his equally trustworthy assistant would know of Sano’s trip here today.

“A man in your position can’t be too careful,” Dr. Ito warned. “But now that you’re here, we may as well get down to business.” He gestured to the barrel. “What have we here?”

“The skeleton of Tokugawa Tadatoshi, the shogun’s second cousin.” Sano described how the boy had disappeared during the Great Fire and today been found buried near the shrine. “I’m hoping you can tell me how he died.”

“Fascinating. I’ll be glad to try.” Dr. Ito called through the open door of the morgue, “Mura-san!”

His assistant came out. Mura’s gray hair had turned silver, and deep lines etched his square, clever face. He was an eta-one of Japan’s outcast class that had a hereditary link with death-related occupations such as butchering and leather tanning. Other citizens shunned them as spiritually contaminated. They did dirty work like collecting garbage and nightsoil. They also served in Edo Jail as wardens, corpse handlers, torturers, and executioners. Dr. Ito had befriended Mura across class lines, and they’d worked together for more than twenty years.

On Dr. Ito’s orders, Mura lugged the barrel into the morgue, which was lit by lanterns and furnished with cabinets, waist-high tables, and stone troughs for washing the dead. Mura pried up the lid. Everyone peered inside at the jumble of dirty brown bones. The only one Sano could identify was the skull.

“Can you tell anything from that?” Marume said doubtfully.

“Perhaps,” Dr. Ito said. “First we must wash the bones.”

Mura fetched buckets of water and filled a trough. He gently removed the bones from the barrel, immersed them, and scrubbed them with a brush. He did all the work associated with Dr. Ito’s examinations that required handling the dead. The dirt came off the bones, but the brown stain from the earth persisted. When Mura was finished, the skeleton lay on the table like pieces of a puzzle.

“Now we put him together,” Dr. Ito said.

He hung a scroll on the wall, an ink drawing of a human skeleton, the bones labeled. Referring to the chart, Dr. Ito picked up the bones with tongs and assembled Tadatoshi’s skeleton. Some small bones from the hands and feet were missing; perhaps they’d been lost at the graveside. But when Dr. Ito had finished, the skeleton appeared almost whole. A moment passed in silence as everyone contemplated the structure that had once supported a human body.

“From the size I deduce that this was a child,” Dr. Ito said.

“Tadatoshi was fourteen when he disappeared,” Sano said.

“He must have died not long afterward. That is to say, he didn’t live to grow up before expiring at the shrine.” Dr. Ito’s gaze moved over the skeleton. “Cause of death can be difficult to determine when the flesh and organs are gone. Let us take a closer look.”

Dr. Ito produced a large, round magnifying lens mounted on a wooden handle. He walked around the table, peering at the bones, pausing to study features through the lens. His eyebrows rose, and he pointed at a thighbone. “Observe this marking.”

Sano, Marume, and Fukida crowded around the table. The marking was large enough for Sano to see without the lens. It appeared to be a crack in which black dirt remained stuck.

“Here’s another,” Dr. Ito said, “and another.” He indicated similar markings on the ribs, the arm bones.

“They look like the cracks in oracle bones,” Fukida said.

The serious, scholarly detective was referring to the animal bones used in magic divination rituals. Fortune-tellers heated pokers in fire and applied them to the bones, causing cracks to form. By interpreting the shapes and patterns of these cracks in the “oracle bones,” they read the future.