Director Zack Snyder revealed a few details about the plot of the movie Xerxes:
"This movie follows Themistocles and the Battle of Artemisium, which coincidentally happens on the exact same three days as the Battle of Thermopylae [which was the basis of 300]. This one starts off with a quick retelling of the why of the Persian wars. It starts off at the Battle of Marathon and then it goes back to Themistocles finding out that Persians are invading again. and off we go over to learn a little bit about why Xerxes is the way he is."
Director Zack Snyder
