The Spartacus War by Barry Strauss (nonfiction)

This book was some of the best nonfiction I've ever read in terms of an exciting narrative that brings a new understanding of the topic to the reader.  Strauss achieves this by organizing the book chronologically and explaining with each new section how much we know from contemporary accounts, later ancient sources, and archaeological sources.  He's very clear exactly when he goes into what could have happened in the context of what is known.