It just so happens that the a beloved Pope had just died in preceding days and the Cardinals were beginning to start conclave to elect a new Pope. Just as the Cardinals head to conclave, four Cardinals go mysteriously missing and the Illuminant's vow to execute a Cardinal on each hour at the four altars of science. With the threat of the antimatter hidden somewhere in Vatican City/Rome and thousands of people gathered in Vatican Square, Langdon and his team must race against the clock to find the antimatter and discover the hidden clues that lead them to the ancient Illuminati altars of science.
This was a fantastic read and I really wish I had it read it much earlier before now. I finished the book before I headed off to the theater to see the film and I thought that the film was pretty decent. They left out quite a bit of detail surrounding the history of the Illuminati, CERN, and Vatican City in general but there so only so much you can do in a movie. I'd read the book just specifically for those elements. They also changed a bit about some of the ending details but the basic elements were there and I can see why they did what they did. Overall though, I found the book much more exciting. But, isn't that always the case?