For nearly 80 years, a huge portion of coastal South Africa was closed off to the public. With many of its pits now deemed "overmined" and abandoned, American journalist Matthew Gavin Frank sets out across the infamous Diamond Coast to investigate an illicit trade that supplies a global market. Immediately, he became intrigued by the ingenious methods used in facilitating smuggling - particularly, the illegal act of sneaking carrier pigeons onto mine property, affixing diamonds to their feet, and sending them into the air.

Entering Die Sperrgebiet ("The Forbidden Zone") is like entering an eerie ghost town, but Frank is surprised by the number of people willing - even eager - to talk with him. Soon he meets Msizi, a young diamond digger, and his pigeon, Bartholomew, who helps him steal diamonds. It's a deadly game: Pigeons are shot on sight by mine security, and Msizi knows of smugglers who have disappeared because of their crimes.

From the mining towns of Alexander Bay and Port Nolloth to Kleinzee's shores littered with shipwrecks, Frank investigates a long overlooked story. Weaving interviews with local diamond miners who raise pigeons in secret with harrowing anecdotes from former heads of security, environmental managers, and vigilante pigeon hunters, Frank reveals how these feathered bandits became outlaws in every mining town.