While poring over dust-caked pamphlets in the library, Ben Rawlence stumbles upon the photo of a lost city of colonial Congo--a glistening, modern metropolis built by huge tin mines and European capitalists. Today, that city, Manono, sits beyond the infamous "Triangle of Death," in an area rarely reached by outsiders since war turned the country's rivers to blood.

In this compelling debut, Rawlence sets out to gather the news from this ghost town in one of the most dangerous places in the world. Ignoring the advice of locals, reporters, and mercenaries, he travels by foot, motorbike, and...