If everything you believe in is being threatened by forces beyond your control, would you pull the trigger of a gun? A small-time crook stumbles upon a body hanging from a tree; a veteran from a Belgian marching band is killed in a hit and run incident, and another dies of an apparent heart attack. Excitement on the streets of Edinburgh is feverish as the city prepares for a huge rally to celebrate the return of Pope John, the 25th, to his home town. With the whole world watching, the security has to be bullet proof. But, is there a chink in the armour, and does Bob Skinner have the inner strength to find the answer to the biggest question of all?