The man’s face darkened. “I was outbid. By an interloper from the city who didn’t know a bee from a bull’s foot about milling. Throwing around bags of money and acting like a lord. The only smart thing he did was hire Abel Coombe to run the place, and where do you suppose he found him?” He poked his chest with his thumb. “Here. At my mill. He stole him from me.”

“Did that make you angry?”

Carlyle’s gaze sharpened, and he didn’t answer for a long moment. “Of course it did. But that was three years ago. I’ve moved on, replaced Coombe with another manager, and gotten back to the business of grinding grain. I lost out on the mill and had my manager pinched, and I thought the best course of action would be to mind my own affairs and ignore what was happening downriver.”

Sensible, but Daniel wondered what else lurked behind that pragmatic exterior. “Sir, if that was your intention, to ignore Montgomery and his mill, why were you in his office in Hammersmith on the morning of the explosion?”

Eyes shifting from Daniel to Owen and then to the clock on the wall, Carlyle finally said, “It was a private matter.”

“There is no privacy in a murder investigation, sir.”

The corners of the miller’s mouth went down, and his eyes grew hard. But he said nothing.

“If I told you I had a witness who would testify that he heard the two of you arguing in Garfield Montgomery’s office, and that you challenged him to a duel, he would be lying?”

Again, nothing. But a flicker of concern flashed across Carlyle’s face. Dueling was illegal, though rarely prosecuted.

“What would cause a man to challenge another to a duel? Dueling is often more a matter of pride than of honor, regardless of the participants’ claims. And what wounds a man’s pride most?” Daniel uncrossed his legs and leaned forward. “Could it be that you suspected Montgomery of not minding his own business? Could it be that you suspected him of having an affair … with your wife?” He said it baldly and forcefully, waiting for a reaction.

With stony features, Carlyle slowly rose. Daniel followed suit, balancing on the balls of his feet, body tense.

“Gentlemen, our interview is finished. I want you to leave now.”

“Sir, there is a murder to solve. Would you prefer we take you into custody and continue our interview at Newgate?”

“You’ve no grounds to arrest me.”