During a Papal Conclave, voting Cardinals are allowed no access to the outside world. In Angels & Demons, the four top contenders are missing - kidnapped from their Vatican rooms - before the Conclave begins.
As a result, Professor Robert Langdon has been summoned to the Vatican. His job is to interpret clues to their whereabouts (and prevent their murders).
Langdon has another, even more urgent, task. As it happens, a cannister containing antimatter has been stolen from a CERN laboratory. As long as antimatter, in a cannister (or in anything else), is not touching the container in which it’s housed, all is well. However, as we have learned, if antimatter comes into contact with matter (such as the sides of a cannister), annihilation (in a light-filled, high-energy explosion) will take place.
Sophisticated clues, which an assassin has devised for anyone who wishes to stop him, are at angel sculptures or reliefs in Rome and Vatican City. Each clue is also associated with a form of matter: Earth, Air, Fire and Water. (Ancient Greeks believed that everything in the world was made from one of those substances.)
In order to find the clues, Langdon and his cohorts must follow the Path of Illumination (which has been orchestrated by the assassin). Let’s tag along:
And ... while he’s tearing around Rome and the Vatican at breakneck speeds ... Langdon must also make a stop at Castel Sant’Angelo. Tthe former papal fortress, which began its 1800-year existence as Emperor Hadrian's tomb, is reached by crossing the Bridge of Angels. It has a safe passage (the Passetto di Borgo) which connects the castle to St. Peter's Basilica.
The professor doesn’t quite get where he needs to be, at the time he needs to be there, however. So ... does that mean the cannister of antimatter (which is being held in place by battery-operated magnets about to run out of power) will explode and decimate most (or all) of Vatican City?