Graphic novelist Frank Miller (300, Sin City) is currently at work on a prequel to the 2007 swords-&-sandals epic 300. Entitled Xerxes, the story is set ten years prior to the Battle of Thermopylae.

Miller tells the LA Times:

It’s the Battle of Marathon through my lens. I’ve finished the plot and I’m getting started on the artwork.

Xerxes succeeded his father Darius the Great as ruler of the Persian Empire in 486 BC, four years after the defeat at Marathon. He was portrayed by Rodrigo Santoro (“Lost”) in the film 300. It’s my guess that Miller’s prequel will follow Xerxes’ journey to the throne.

300 director Zach Snyder has already expressed interest in directing the project, though nothing is official as of yet. 300 has grossed over $450 million worldwide.

(UPDATE: PREQUEL GETS NEW TITLE & DIRECTOR)