On a hot, still night in June 1965, a soldier walked into the town of Monte Plata, in the Dominican Republic, to report that he had accidentally shot dead two policemen. There was more, though. Next to their bodies was that of a young Canadian Catholic missionary, Father Arthur MacKinnon, killed in circumstances that, at the very least, appeared obscure. 

The official version was that he had died after refusing to stop at a roadblock, but there was no blood in the car and the bullets had entered him at close range, from behind. To the other priests who buried him, it seemed certain that he had been