On the Maroni River, along the border between French Guiana and Suriname, Brazilian garimpeiros dredge for gold from makeshift barges. Motor pumps roar, long hoses plunge to the riverbed, and divers—supplied with air from the surface—guide the suction pipes through the silt in search of nuggets.

When a seaplane and its pilot are drawn into this wild gold rush, the adventure takes a darker turn: greed, traps, and shifting loyalties in the heart of the Amazon.