“Did you know that Erhard Riker was adopted?”

“You don’t say? No, I didn’t.” Weintraub gazed across a sea of workbenches where jewelers labored in pure north light streaming through tall windows A speculative smile played on his lips, and he stroked his chin. “That explains a lot.”

“What do you mean?” asked Bell.

“He was such a nice man.”

“The father?”

“No! His father was a cold bastard.”

Bell exchanged incredulous glances with Archie Abbott.

The factory owner noticed. “I am a Jew,” he explained. “I know when a man dislikes me because I am a Jew. The father hid his hatred in order to conduct business, but hatred seeps out. He could not hide it completely. The son did not hate me. He was not so European as the old man.”

Bell and Archie exchanged another look. Weintraub said, “I mean, he acted like a good man. He was a gentleman in business and kindly in person. He is one of the very few people I buy from who I would invite into my own home. Not a man who would shoot up a jewelry shop on Maiden Lane. Not a bigot like his father.”

Archie said, “So I suppose you were not that upset when his father was killed in South Africa.”

“Nor was I surprised.”

“I beg your pardon?” asked Archie, and Issac Bell said sharply, “What do you mean by that?”

“I used to joke to my wife, ‘Herr Riker is a German agent.’ ”

“What made you say that?”

“He couldn’t resist boasting to me of his travels. But I noticed over many years that somehow his trips always led him to where Germany was making trouble. In 1870, he just happened to be in Alsace-Lorraine when the Franco-Prussian War broke out. He was on the island of Samoa in ’eighty-one when the United States, England, and Germany instigated their civil war. He was in Zanzibar when Germany stole her so-called East African Protectorate. He was in China when Germany took Tsingtao, and in South Africa when the Kaiser egged on the Boers fighting England.”

“Where,” Archie noted, “he was killed.”

“In an engagement led by General Smuts himself,” said Isaac Bell. “If he wasn’t a German spy, he was a master of coincidence. Thank you, Mr. Weintraub. You have been very helpful.”

On their way back to New York, Bell told Archie, “When I accused O’Shay of repaying the man who adopted him by becoming a murderer and a spy, he answered that rescuing Katherine from Hell’s Kitchen was ‘one’ of the ways he repaid him. He said, ‘I say it with pride.’ I realize now that he was bragging that he followed in his adopted father’s footsteps.”