The film tells the story of the payador José Betinotti, a mythical character in Argentine music. It faithfully reconstructs the scenarios of the early twentieth century: the workers' struggles, the party meetings of the caudillos and the circus criollo, the cradle of Argentine theater and music.

The plane of a military man falls in an isolated area of the forest and, in time, he becomes a man-beast, a troglodyte. He is found by a scientist who turns him into a guinea pig for an experimental potion. The experiment fails and the troglodyte becomes a satyr who attacks and kidnaps maidens to take them to a cave where he subjects them to atrocities.