The pope is dead. Cardinals are beginning to arrive at the Vatican to select his replacement, but one has fled for Malta in search of a document that dates back to the 4th century and Constantine the Great.
Former Justice Department operative Cotton Malone is in Italy, on the trail of legendary letters between Winston Churchill and Benito Mussolini that could re-write history. But someone else is after the same letters and, when Malone obtains and then loses them, he's plunged into a hunt that draws the attention of the legendary Knights of Malta.
The knights are the only warrior-monks to survive into modern times. Now they are a global humanitarian organization, but within their ranks lurks the Secreti - an ancient sect intent on affecting the coming papal conclave. Malone races the rogue cardinal, the knights, the Secreti, and the clock to find what has been lost for centuries. Meanwhile, the election of the next pope hangs in the balance.