Tale of revenge and monsters set in the Amazon jungle, with Burr not sure if he is turning into a gorilla-like monster or going crazy.
Much better than its PD status and exploitative title would indicate, but it is safe to say Sidomak was a better writer than director. The whole cast is good, but Chaney fares best, even if he's probably not the first casting choice that comes to mind for a Brazilian police commissioner. . .
Incidentally, the monster depicted in the film, the succarath, is a "real" cryptozoological beast, though it was from Patagonia and not the Amazon rain forest.