When Father Donald McNulty, a gentle parish priest from the Cotswolds, makes one of his regular visits to family in Canada, he does not expect to be caught up in an incident that will lead to frantic discussions at the highest level aimed at averting possible international conflict. After an explosion, mysterious fragments, evidently from some book or other, rain down while he camps in the wild interior of the Algonquin Park, a vast, untamed area of Ontario. Unaware of their nature, he brings the fragments back home with him, but soon finds others will stop at nothing to get hold of them....