Blackbox

Cross a road, take a train, or get on an airplane and you put your life in the hands of a stranger -- every bit as screwed up, every bit as fallible and as human as you are. Then the person turns out not to be a stranger at all, and suddenly it's much worse.

In America and Britain and the sky in between, an apparently disparate group of people is connected, whether intimately or by chance, to the t...