Angels and Demons- Before Reading

So far I have heard a lot about the book, but I am not exactly sure what it is about. I know that the author, Dan Brown has written several other books, such as the Da Vinci Code. I am also aware that there has been a movie made for this book, and the Da Vinci Code, which I plan on watching after I finish the book. I believe that the book covers the topic of the Illuminati, a very secret group. What I know about them from a small amount of research I did is that this group of people were against Christianity and the group consists in many powerful people in history. My dad read this book and told me it is in the mystery genre, so I am looking forward to surprises while reading.