King Leonidas, who leads 300 Spartans into battle against the Persian "god-King" Xerxes and his invading army of more than 300,000 soldiers. As the battle rages, Queen Gorgo attempts to rally support in Sparta for her husband. The Spartan defeat was not the one expected, as a local shepherd, named Ephialtes, defected to the Persians and informed Xerxes of a separate path through Thermopylae, which the Persians could use to outflank the Greeks..