Yet it seemed impossible. Makino and Yanagisawa had been cronies for the entire fourteen years of the shogun’s reign. Not a hint of a rupture between them had Sano ever heard.

“Makino would never have betrayed my master,” Ibe burst out. “His loyalty was absolute. He wouldn’t have deserted the chamberlain, especially at a time like this!”

“I regret to disappoint you, but he did.” Daiemon’s callous tone said he wasn’t at all sorry.

“Why would Makino defect?” Sano said, still disbelieving.

“I persuaded him that our faction was likely to be the victor in a war against Chamberlain Yanagisawa,” said Daiemon, “and he wanted to be on the winning side.”

Ibe started to protest, then fell silent. He looked as though his perception of the whole world had changed. Sano realized that Daiemon’s story could also change the course of the murder investigation.

“So you can see that I had no reason to kill Makino,” said Daiemon. “He wasn’t the enemy any longer. With him on our side, we had a majority on the Council of Elders. He could influence the shogun in our favor. It was in my interest for him to stay alive.”

If the story were true, Sano thought. “Who besides you was aware that Makino planned to switch sides?”

“My uncle was,” Daiemon said.

Sano glanced at Lord Matsudaira, who nodded. Sano realized that he’d known all along that his nephew had been at the crime scene. He’d never denied it.

“Did anybody else know about the defection?” Sano said.

Daiemon shook his head. “We meant to keep it a secret.”

“Why?”

A sly smile curved Daiemon’s mouth. “It was better that Chamberlain Yanagisawa didn’t know Makino had turned traitor. We wanted to use Makino as a spy in the enemy camp.”

“Then I have only your word, and your uncle’s, that Makino did betray Chamberlain Yanagisawa and join you,” Sano said.

Daiemon shrugged, unperturbed by Sano’s hint that he and his uncle had concocted the story. “It’s the truth.”

“Is it also true that you and Makino had an argument that night?” Sano said, recalling what the guards had told him.

“Yes,” Daiemon said promptly. “Makino demanded a bribe in exchange for his allegiance. It was more than I wanted to pay. We haggled over the price. Finally we struck a deal.”

But Sano conjectured that Daiemon could have invented this explanation because he knew about Makino’s obsession with security and had anticipated that a spy in the house would overhear the argument. Maybe Makino had intended to defect, but when Daiemon balked at paying a bribe, Makino had changed his mind. Daiemon wouldn’t have taken kindly the loss of a potential major ally, and he’d have seen the advantage of eliminating Makino. With Makino gone, and Chamberlain Yanagisawa’s influence over the shogun weakened, Daiemon had an even better chance at the succession. The murder of one frail, helpless old man could have ensured his place at the head of the next regime.

“Then what happened?” Sano asked.

“We said good night,” Daiemon replied. “I went home.”

“Did you leave the estate right away?” Sano asked. When Daiemon nodded, he said, “No one there saw you leave.”

Daiemon chuckled. “I played a little joke on the guards and took a shortcut. There’s a gate in the back wall. It’s small, overgrown with ivy, and barred shut. I doubt if it’s ever used. Probably the guards don’t know it exists. They weren’t watching it that night. I slipped out the gate, with them none the wiser.”

Sano planned to look for the gate, which he didn’t doubt he would find. He said, “If the guards don’t know about the gate, then how do you?”

“I grew up in Edo Castle. When I was a boy, I explored every part of it. I amused myself by sneaking into places where I didn’t belong.” Daiemon smiled at his youthful daring. “I’ve been inside most of the estates, including the one you live in now. By the way, you’d better seal up that trapdoor outside the kitchen that leads to the cellar, if you haven’t already.” He laughed at Sano’s disconcerted expression, adding, “I must know Edo Castle better than anyone else does.”

His knowledge, and talent for stealth, might have come in handy years later. Sano imagined Daiemon sneaking back to the private quarters while Tamura and the guards searched for him, beating Makino to death, then fleeing out his secret escape hatch.

“There’s evidence that someone broke into Makino’s quarters,” Sano said. If Daiemon had returned to kill Makino, he couldn’t have entered through a door because the guards would have seen him.

“It wasn’t me,” Daiemon said with brazen nonchalance. “And I didn’t kill Makino. He was alive when I left his estate.”

“Can anyone vouch for your innocence?” Sano said.

“No, but you have my word. And my word carries a lot of weight these days.”

Daiemon’s smug smile alluded to his relationship with the shogun. Sano knew he was no meek sexual slave to his lord but a man who used his body and charm as weapons to get what he wanted.

“To accuse my nephew of murder would be a big mistake,” Lord Matsudaira said, clearly hinting that the shogun would protect Daiemon and punish Sano for maligning his lover.

“I may have no choice,” Sano said.

Honor required him to pursue the investigation no matter what. He’d reached a fork in the path of his inquiries. One branch led to Daiemon and Lord Matsudaira, and a perilous clash with them should his findings implicate them in Makino’s murder. The other branch pointed the way to a new suspect who could be just as dangerous.

Daiemon grinned. “You’ve got a choice between sticking your neck in front of the executioner’s blade or walking into fire, Sōsakan-sama. Because you and I both know there’s someone besides me who bears investigation. Someone who’d have done anything to keep an ally from defecting-or to punish a traitor.”

“Betrayal by Makino would give Chamberlain Yanagisawa a motive for murder,” Sano said.

“It would have put him at a serious disadvantage against the Matsudaira clan,” said Hirata.

They were walking through the army camp in the Tokugawa enclave, away from Lord Matsudaira’s estate. Otani dogged their heels, while Ibe trailed behind them. Dark gray clouds still blanketed the sky, threatening more rain. Mutters and laughter emanated from soldiers huddled around fires and in tents.

“Makino’s defection might have cost the chamberlain control of the regime,” Otani hastened to add, removing aspersion from his master by shoveling it upon the enemy.

“And here I thought that for once Yanagisawa was above suspicion,” Hirata said.

“My master wasn’t responsible for the murder,” Ibe said, but he spoke with much less conviction than before.

Glancing backward, Sano noted how shriveled and sick Ibe looked. He must be dreading how his master would react to Daiemon’s insinuations. Yet Sano understood that although things looked bad for Chamberlain Yanagisawa, his role in the murder was debatable.

“The question of Yanagisawa’s guilt or innocence hinges on two issues,” Sano said. “The first is whether Senior Elder Makino really was going to defect. The second is whether Yanagisawa knew.”

“If he didn’t know-or if Daiemon lied-then he had no reason to assassinate Makino.” Hope brightened Ibe’s voice. “As far as he knew, Makino was still his ally.”

“Even if Daiemon told the truth about the defection, he claims it was a secret,” recalled Hirata. “According to him, Yanagisawa couldn’t have known. Yet he wants us to believe that Yanagisawa killed Makino for betraying him.”

“Daiemon was telling us that although only he, his uncle, and Makino were supposed to be in on the secret, no secrets are safe from Yanagisawa,” said Otani. “But let’s not waste time debating the issue. There’s one way to settle it: Accuse Yanagisawa publicly and hear what he has to say for himself.” Eagerness to ruin the chamberlain blazed in Otani’s eyes.