The dam on the Rio Araçu is the dream of a lifetime for Quincy, a design engineer, and it matters little that the resulting huge reservoir is a veritable tombstone for the Arara indios. But this is not the only reason for the tensions that hang thick in the air at the construction site. Strange accidents, deliberately caused deaths and lynchings are just the prelude to the great tragedy which is about to occur. Engineers Nick and Sheila Martins, entrusted with inspecting the works, discover something that could cost them their life, unless Mister No and the proud warrior Guaranay intervene...