When his beloved son lands in the clutches of the sinister Earth goddess Gaea (Gia Sandri), Hercules (Reg Park) bravely ventures deep into the netherworld to rescue him, battling a host of ghouls, zombies and monsters in the process. Upon his return, the great Grecian hero discovers that his son's kidnapping was all part of Gaea's evil ploy to have her own son, Antaius, take over Hercules's throne.