The search for a professor's daughter who has disappeared somewhere in the Amazon jungle leads adventurer Ulysses Vidal to the Black City. Its ancient structures, as if created for the Cyclopes, and the contents of the pyramids amaze the imagination. The whole world should know about this discovery. But it was not there. Among the impenetrable jungles, real monsters are hidden - half-humans, half-animals... And they are ready to destroy any stranger who invades their territory...