The film opens with the statement that the people of Troy must once a month sacrifice a maiden lest a sea monster destroy their city. Because of this, some families flee Troy only to be captured by pirates. Hercules (Gordon Scott), aboard the ''Olympia'', comes across one of these ships and frees the Troy aboard. Going to Troy, Hercules is given use of two horses that cannot be wounded by arrows. He then learns from Ortag (Roger Browne) the monster's weakness: its armor doesn't cover its belly.