The Vatican sends Father Michele Deauchez to investigate a Mary sighting in Santa Pelagia, Mexico. The sighting is a most unusual one. Twenty-four religious leaders from around the world of various faiths claim they were led to the tiny village by a dream. Each of "The Twenty-Four'" saw a divine entity in Santa Pelagia  -- some saw Mary, some Kali, some an angel.  But the message was always the same: the end of the world was at hand.  Each was given the same prophecy to relay to the press to prove the divinity of the Santa Pelagia message -- that in a few days time a plague of sores would occur, starting the signs of the end times.

Deauchez's training pre-seminary was in psychology, and he has always been a voice of reason and skepticism in the Vatican.  He feels certain that the message is not divine -- despite his own bizarre experiences in Santa Pelagia.  He begins to investigate The Twenty-Four, aided by New York Times reporter Simon Hill.  As they probe the mysteries of the prophets they uncover confusing evidence of both divine and human interference.  The plague of sores appears and is rapidly followed by signs foretold by doomsayers from Nostradamus to the Native Americans.  As the loss of life escalates and even hard-core agnostics begin to believe, Deauchez and Hill manage to survive and evade, continuing to probe deeper, searching out the final missing two prophets of "The Twenty-Four" in hope of understanding.

Is the message of Santa Pelagia divine or a conspiracy? The answer, as Deauchez and Hill learn, is not a simple one.