Free on Gutenberg or Internet Archive.
Wikipedia: Pinkerton Detective Agency
Reading in progress blogged about here.
2 1/2 Stars mainly for dull use of exciting stories and because it's not going on my Would Read Again list. Almost made 3 but some of the period stereotypes changed my mind (more on that nearer the end where I eyeroll over it).
This book is basically the true crime of the late 1800s. Unfortunately it's not as interesting as it should be - even with some really great crime stories the author makes them drag on in parts. I found it interesting here and there, but more as obscure history. (I do have a couple of other (free) Pinkerton books to read, but these were ones written by Allan Pinkerton. They're supposed to be really self promotional, so I'm curious to see how he'll write about himself.)
You could file these under history - but I'd really call them history-ish, or true crime. Mainly because the author is getting his material - I assume - from the Pinkerton archives. There's no preface so he may not have been able to interview any of the Pinkertons himself - who knows. True crime is always a slightly suspect genre for good reasons - it has a long history of being purposefully graphic to entice readers to buy it. Being factually accurate wasn't really a priority - telling a story was. But the author here isn't really going for graphic details or good story telling - this is far more police procedural type stuff. But again, not as exciting as that sounds. (It makes you wonder how much the author actually wrote and how much was just quoted directly from the files.)
As usual, I think the best idea I can give you about the book is to quote some parts of it. And also as usual, I'll warn you that the bits I've chosen may make the book seem more interesting than the whole thing actually is. (I should also add that I used this as one of my Books To Fall Asleep To, which I pick on purpose not to tempt me to stay up later in order to keep reading.)