“Angels and Demons” was written by Dan Brown before he wrote his bestseller novel “The Da Vinci Code”. As such it shares the same protagonist Harvard symbologist Robert Langdon and a plot revolving around medieval Christian mysteries. The story is about an ancient brotherhood named Illuminati and its alleged attempt to blow up Vatican City using antimatter.
The novel is decent by itself and the latter half is quite gripping, but it does not measure up to the vastly expanded scope of the sequel. If you liked the sequel, you'll most probably like this one too. John Langdon has created some really nice ambigrams for this novel including an “ambigram of ambigrams”.