My cousin recommended this book to me and I'm glad he did. It's less a book and more a collection of Frank Sheeran's recorded "confessions." Sheeran was involved with the mob and admitted to being the one to kill Jimmy Hoffa. I don't want to spoil too much of the book, but there are some interesting parts related to JFK's assassination that make a lot more sense than the conspiracy theories.
Brandt tries to explain the background, but I found his parts to be the weakest in the book. Sheeran's dialogue is often hard to follow because he's deliberately obtuse. They were constantly worried about wire taps so they spoke in code - a lot of "this thing we had to do" and so on. After a lot of "things" get mixed together, it can be hard to follow the thread.
I liked the first half better than the second, but I still highly recommend it.