Greek general Themistocles attempts to unite all of Greece by leading the charge that will change the course of the war. Themistocles faces the massive invading Persian forces led by mortal-turned-god, Xerxes and Artemesia, the vengeful commander of the Persian navy.

Based on Frank Miller's graphic novel, "300" is very loosely based the 480 B.C. Battle of Thermopylae, where the King of Sparta led his army against the advancing Persians; the battle is said to have inspired all of Greece to band together against the Persians, and helped usher in the world's first democracy.