Oliver Bullough traveled from London to Kiev, via Odessa and Cyprus, to trace the money trail from one Ukrainian oligarch. In doing so, he discovered the intricacies of the kind of international corruption that results in a trillion dollars being syphoned out of the world's poorest countries each year—and stashed in the West. His project highlights why it is so hard to do anything about this problem, an issue which is under-reported because of its sheer complexity.