His brazen declaration left Sano speechless. Had Matsui’s “confidences” been nothing but a joke at his expense? Or was Matsui bluffing now, to repair the damage they’d done?

“As for the nights of the murders,” Matsui continued in the same recalcitrant tone, “I was here at home, in this very room.” Pointing at the men outside the door, he added, “My guards will vouch for me. I never go anywhere without them.

“And now you must excuse me, sōsakan-sama; I have business to conduct. If you have any more questions, you’ll have to arrest me. But think hard before you do. Should the shogun’s gold cease to multiply and flow, I doubt if he would thank you.”

Sano returned to Edo Castle at noon, feeling rushed and discouraged. Now, he rode through the main gate to seek Chūgo Gichin, captain of the guard and second suspect, before attending his miai. Since he couldn’t conduct a secret inquiry in the castle, where spies would undoubtedly report his activities to Chūgo, he hoped a surprise confrontation might prove more satisfactory than his clash with Matsui.

He couldn’t eliminate Matsui as a strong suspect, despite the merchant’s denials and the common sense that told him such a man wouldn’t risk his wealth and position to revive a dead feud. He believed in Matsui’s sinister obsession with General Fujiwara, and had sensed his capacity for violence. During their short encounter, he’d grasped Matsui’s essential nature: bold, ruthless, with a grandiose self-importance that could easily inspire a sense of invincibility. That Matsui’s associates would attest to his good character and his bodyguards to his whereabouts didn’t convince Sano of the merchant’s innocence. All those people were in Matsui’s pay. Still Sano appreciated the difficulty of establishing Matsui’s guilt.

Matsui was far too clever to leave incriminating evidence in his places of residence or work. Sano thought he could probably persuade Matsui’s enemies to contradict the good references from friends and underlings, but he doubted whether he could break Matsui’s alibi. If the bodyguards had taken part in the murders, they would lie to protect themselves.

This next interview would either offer a better suspect, or eliminate Chūgo Gichin and give him more time to incriminate Matsui. Of Chamberlain Yanagisawa, he could not bear to think, because Yanagisawa’s guilt would mean his own destruction. For once, Sano closed his mind to his father’s voice, which would force him to acknowledge the possibility he didn’t want to face.

Inside the castle, Sano entered the main guard compound, where a thousand samurai occupied the huge, stone-walled courtyard shadowed by the towering keep. Some were mounted, others on foot; all wore swords and armor tunics. The long wooden sheds that bordered the compound held an arsenal of swords, spears, bows, polearms, arquebuses, cannon, and ammunition. This was the mighty heart of the Tokugawa military regime. Through it, like an emperor surveying his domain, strode Chūgo Gichin.

Accompanied by three lieutenants, he alone wore full battle regalia. A black metal helmet with deep side flaps and a pair of carved golden pine boughs adorning its crown sat proudly on his head. An elaborate armor tunic, its many plates laced with red and gold silk cord, hung from his high, square shoulders. Chain-mail sleeve guards covered his long arms. His kimono hem was tucked into metal shin guards that covered legs as slender and straight as wooden pillars. His erect, rigid posture emphasized his spare muscularity. As he made his inspection tour, he carried the weight of his armor without visible effort. His voice, barking orders and questions at his ranks, rose above the sounds of footsteps, hoof-beats, and muted conversation.

Sano watched the captain of the guard and tried without success to imagine him a murderer. This man’s family had loyally served the Tokugawa for generations. Chūgo had worked his way up through the military ranks, even doing a stint in the navy. Now he was responsible for the castle’s security during his duty shift. It was his job to protect the shogun, his family, and their multitude of officials, retainers, and attendants; to maintain order and peace.

How could he also be the person who had killed four men and thrown the city into turmoil?

Then Chūgo headed toward his command post, passing the armory sheds, whose red curtains bore his crest: a white octagon with the Fujiwara crescent moon in the center. Sano dismounted and started after Chūgo. Before he'd moved ten steps, a pair of guards accosted him.

“May we be of assistance, sosakan-sama?” one asked. A touch of insolence tainted his courteous bow and greeting. Just three days ago, these men would have treated Sano with fawning subservience. He marveled at how quickly news of his downfall had reached even the bakufu's lower echelons.

“I must speak with Captain Chūgo Gichin,” he said.

Scornfully looking him up and down, they advanced until he was forced to move backward toward the gate.

“It concerns a matter of vital importance to castle security,” Sano added.

The two guards stopped, exchanged glances, shrugged. “Come with me,” the spokesman said.

Sano offered a silent prayer of thanks for underlings who preferred to shift responsibility to their superiors. Shadowed by his escort, he followed Chūgo's steps to a large shed in the compound's corner, built under a tall watchtower. He braced himself, hoping his arrival would startle the captain into betraying guilt. But as they entered the command post, the guard shot an arm across Sano's chest.

“Wait,” he ordered.

The post's anteroom was unfurnished, earth-floored. An open door at the rear showed the captain's office, which contained a desk, cabinets, chests, pieces of armor and weaponry. The walls were covered with duty rosters and maps of the castle. Sano's attention flew to the room's center, where Chūgo Gichin knelt on a straw mat, profile to the door, fists balled on his thighs. He'd removed his armor and helmet; now, a black hood completely covered his head. An attendant was positioning four man-size straw dummies around Chūgo. Finishing, he came to stand beside Sano at the door. He raised a finger to his lips for silence. Sano nodded agreement, eyes riveted on Chūgo. Anticipation tightened his stomach. He was about to witness a demonstration of the martial arts skill for which Chūgo had achieved nationwide fame: iaijutsu, the art of simultaneously drawing and cutting with the sword.

Chūgo sat perfectly still; he appeared not to breathe. But Sano sensed the mental energy flowing from him as his trained perception divined the positions of the unseen targets. While Sano waited in suspense for Chūgo to draw his sword, he wondered what the captain's proficiency at iaijutsu said about him.

Iaijutsu was a discipline particularly suited to peacetime, when samurai kept their weapons sheathed, instead of drawn as in battle. The techniques could be used defensively, or to secure the opening move in a duel. Hence, most reputable kenjutsu masters trained their students in them. But iaijutsu had a treacherous, and therefore dishonorable aspect. Too often it was used against unwary opponents or unarmed peasants. Many of the latter had died in "“crossroad cuttings,” or “practice murders,” when a samurai merely wanted to test a new sword.

Had Chūgo used his deadly skill to strike down Kaibara Tōju, the ronin Tōzawa, and the eta before they'd perceived the danger? Did his choice of discipline imply a willingness to attack helpless or unsuspecting victims? One thing Sano knew: Extreme devotion to the martial arts often indicated an obsessive adherence to Bushido. Had its credo of ancestor worship driven Chūgo to murder?