There are many Illuminati books that have been written in the past. Not only a good book, but a great trilogy, was "The Illuminatus! Trilogy" first published in 1975. Robert Anton Wilson and Robert Shea put together this series of books that exposed many conspiracy theories.
The books jump around in time and give the authors' perspectives on many topics that surround the Illuminati. Doing so creates a world of thinking for the reader, which leads them to continue through the entire series of three books. This trilogy of books later went on to win the Prometheus Hall of Fame Award in 1986.