In the wake of such epics as Troy and Kingdom of Heaven, one imagines director Zack Snyder's 300, about the Roman Battle of Thermopylae, would have had little trouble getting picked up in Hollywood. Not so, says Snyder, whose first film since his 2004 debut Dawn of the Dead scored $70 million at the box office last weekend.

"When I first got the book and took it to the studios, we had no script at all. I was just convinced that everyone would think it was as cool as I did, so when I took it to them I'd say, 'Look, it's a graphic novel, we're going to film this.' And they all said, 'Yeah, we don't really understand this.'" Initial studio reactions didn't faze the thirty-one year old director from seeking out the green light for his bloody yet small-scale actioner, though.

Die-hard fans of the picture will have read the source material, Frank Miller's bestselling graphic novel of the same title. "I love Frank's prose," Snyder gushes, but he notes that other works influenced his direction (just as the comic itself is inspired by the 480 B.C. Battle of Thermopylae and the 1962 film The 300 Spartans). "The success of Sin City helped," he remarks, referring to an earlier adaptation of one of Miller's books. "There's a very strong relationship between Sin City and Frank, and 300 and Frank, that world."

Such guidance didn't prevent Snyder from taking a few liberties with the filmed version, though. The movie faithfully translates Miller's brutal depiction of the conflict between King Leonidas's Spartans and King Xerxes's Persian army; but after the Spartan army leaves for Thermopylae, Snyder and his co-writers add in a steamy subplot with the reigning Queen Gorgo and Theron, an opportunistic councilman.

It took more than three years and several scripts, computer-generated animated sequences and test shots with actors to convince executives at Warner Bros. Pictures to sign off on the project. "Because we had so much prep, the actual process of making the images what they look like was sort of intuitive," Snyder says, "but it was really an exhausting process, just physically shooting the shots."

His "giant war battle movie," as Snyder describes it, was filmed in 60 days on a sound studio in Montreal. Post-production took a year, much of it spent replacing the rough cut's green-screens with hordes of warriors and distinctive goldenrod landscapes. "Our philosophy [on green-screens] was, if you touch it, it should be real - other than a rhino or an elephant. All the fighting is guys fighting guys."

Two such men are the movie's low-key stars, The Phantom of the Opera's Gerard Butler and Lost's newest cast member Rodrigo Santoro. They spent months training in anticipation of their barely-clothed performances. "Gerry's amazing and Rodrigo is awesome, but if you put them in the Us Magazine poll of star power, they'd be probably not as high as Brad Pitt or Bruce Willis," Snyder confesses. "But we really felt strongly about what the movie was going to be, and in some ways I didn't want the movie to pop for you like that."

"And when [Gerard] showed up, he stomped around the coffee shop and he was acting like Leonidas, using these hand gestures from the book ... other people were staring at him, like 'it looks like he's got the part.' I left that meeting thinking he was pretty good"