Nonfiction that reads like a thriller: what kept you up way past bedtime?

I just finished a narrative nonfiction book in two nights and it reminded me how good the genre can be when the author knows how to pace a story. For me the classics here are things like The Devil in the White City and Into Thin Air, but I'd love some less obvious picks. What's the most gripping true story you've read, and was it actually the subject or the writing that carried it?