Q: So did Pinkerton start the Secret Service?
A: No, the Secret Service started out protecting money, not presidents — it was formed to fight counterfeit currency. But Pinkerton was familiar with security nightmares: Lincoln believed that people deserved access to him, so he would hold these "handshaking levees," where a long line of people snaked past to shake his hand like a pump handle. John Nicolay, another staffer, said Lincoln had "a heart so kindly … that it was hard for him to believe in political hatred so deadly as to lead to murder."
Q: Tell me about Pinkerton detective Kate Warne. Another Kate — Winslet — should play her in the movie.
A: [Laughs] She's one of my favorite characters in the book!
Pinkerton's sitting at his desk one day in 1856 when there's a knock on the door and he finds a young woman standing there. [She had dark blue eyes that Pinkerton said were "filled with fire."] She introduces herself as Kate Warne, a widow looking for work. But Pinkerton thinks she means secretarial work, so she says, "I'm afraid you have misunderstood me, sir."
Well, there was no such thing as a female detective in the 1850s, so Pinkerton was "dumbfounded and thoroughly unsettled" to learn she wanted to become one. But he also wanted to give her a fair hearing. So he asked her, "How, exactly, do you propose to be of service?"
Warne was clearly ready for the question. "A female detective may go and worm out secrets in ways that are impossible for male detectives," she told Pinkerton. "A criminal may hide all traces of his guilt from his fellow men, but he will not hide it from his wife or mistress. The testimony of these women can be obtained [by] a female detective [who] wins her confidence." Pinkerton signed her up the next day. She wound up secretly escorting Lincoln to Washington, posing as the caregiving sister of an "invalid" who did not want to be disturbed by other train passengers.
Q: The Hour of Peril is also largely a life of Allan Pinkerton. Who, finally, do you think he was?
A: Pinkerton is a remarkable story. He was definitely a tough nut — a scrappy, grizzled, quick-to-anger Scottish immigrant. He felt secrecy was the lever of his success, so it may also be fair to say he was paranoid — but don't you want that in a detective?
There's controversy about who Pinkerton really was because he later acquired a legacy of union-busting. In fact, someone accosted me by the punchbowl at a PTA meeting recently and blurted out, "Pinkerton broke my grandfather's skull at the  Homestead Strike — are you going to write about that, Mr. Author?" Much as I like being addressed as "Mr. Author," that could not have been Pinkerton, because dead men crack no skulls. [Pinkerton died in 1884.]
So I'm not apologizing for Allan Pinkerton or putting him up for sainthood. But the untold story here is of a barefoot cooper who came to the United States and became the country's first private eye. That term came from his logo, by the way: It had this stern, unblinking eye and the motto "We Never Sleep." Thank God he didn't.
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