The titular monster is the multi-headed Hydra, a familiar figure in sword-and-sandal epics. The hero, played by Reg Lewis, must undergo several daunting tasks before he is considered worthy of combat with the Hydra. Though episodic, the film holds together pretty well. It is compromised only by the inconsistent camerawork and the crude English dubbing. The hero, incidentally, isn't really a "Son of Hercules"; he has been so designated so that the film will be compatible with the Sons of Hercules package syndicated to American TV stations in the early 1960s.