However the book did have some interesting information about Worth, as well as William Pinkerton, son of Allan, the founder of the detective agency. Macintyre describes Allan as a strict, dour father, and William as a semi-rebellious son who often befriended criminals despite being a detective. William Pinkerton meets Adam Worth a few times and treats him respectfully, such that Worth later on asks Pinkerton to help him sell the Gainsborough painting back to the art dealer he stole it from. The Pinkertons apparently had quite a massive file on Adam Worth's career and crimes, but they never had any proof that they could use to arrest and convict him, so they just monitored him and his accomplices for years.
William Pinkerton apparently respected Adam Worth for being a "gentleman thief" who was smart and didn't resort to violence or murders (unlike the fictional Moriarty). Pinkerton also apparently sympathized with Worth when he was eventually caught and betrayed by former accomplices. (The prison he was in really sounds horrific, and Worth's health was ruined afterward.) Thus Pinkerton eventually helped Worth sell the painting back, for the sake of Worth's innocent children who needed financial support, and he protected Worth from getting arrested for the theft, by stretching the truth when he negotiated with Scotland Yard and the art dealer. Even after Worth died, William Pinkerton still showed kindness to Worth's children, by sending them money and eventually hiring Worth's son in the agency.
Even more astonishing, in the Epilogue, Macintyre explains that many criminals were treated this way, not just Worth because he was special.
William Pinkerton was increasingly their protector and benefactor, sending magazines, money, Thanksgiving turkeys, and even clean underwear to men he had helped land in prison. Many former felons found employment in the Pinkerton Detective Agency.
I find this very interesting, though I somewhat doubt Macintyre's point that William was rebelling from his father Allan in this way. It seems rather a family trait.
Earlier, when I was reading Allan Pinkerton's books, he claimed that his detectives have sympathy for the criminals they catch. So either he shared the sympathy, or Allan's book (which may have been ghostwritten) was altered to express William Pinkerton's sympathy for criminals. I'm sorry I doubted Allan Pinkerton now, and I suppose I shall imagine that Kate Warne made up with Mrs. Maroney somehow and that some criminals were treated well once they were caught. Too bad the Pinkertons couldn't muster some sympathy for the unions they busted during some of their jobs.
I wish the book would speak a little more about William's brother Robert (not to be confused with their uncle Robert) who ran the New York branch, which is where I want to place Sherlock Holmes for a year in my novel, but Macintyre seems to find him a less interesting person. There is some discussion of Moriarty's similiarities to Adam Worth, but it's late in the book. He also includes a Sherlockian theory that Gruner from "The Illustrious Client" is based on Worth too, but I think that was stretching it a bit.