A lot has changed since we first met Jason Bourne in 2002 — back when he was a wounded assassin with amnesia being yanked out of the Mediterranean. Back then, Matt Damon may have had Good Will Hunting and Saving Private Ryan under his belt, but he wasn't exactly anyone's idea of an action star. Or a nonaction star, really. But his newfound badassery turned The Bourne Identity into a sleeper hit, taking in $122 million. Since then, the Bourne saga has become one of those all-too-rare Hollywood franchises — the kind that actually get better and better. Not that it's been easy. While making the first film, director Doug Liman clashed so violently with Universal he wasn't invited back for the sequel, 2004's The Bourne Supremacy. Instead, the bullhorn was handed to British director Paul Greengrass. ''At first you think, 'I get to direct a Bourne movie, how lucky am I?''' says Greengrass. ''Then you think, 'Oh, s---!' Because the bar is set pretty high.''

Making the latest chapter, The Bourne Ultimatum, wasn't any easier. For starters, the script was being written on the fly (when there even was a script) while the crew was hopscotching across three continents. ''There was an aimlessness to the process,'' says Damon. ''It was miserable.'' Then, there's the fact that all of this aimless misery lasted for nearly a year, an eternity in moviemaking time nowadays. And the fact that they didn't wrap until weeks before Ultimatum was due to open. The good news is, it's done (see the EW review). And now, after a summer of empty spectacle and often-joyless bombast at the multiplex, Bourne marks the return of the thinking person's popcorn movie. Says Greengrass, ''I like to think that when Bourne comes on stage at the end of the summer, as he tends to do, it's like a breath of fresh air.'' Agreed. And that's why we sat down with its star (and a few icy margaritas) to discuss the nightmare shoot, life as a married man and father, and how he almost got lassoed into a certain gay cowboy movie.

ENTERTAINMENT WEEKLY: So you didn't have a finished script when you were shooting this. That's generally not the way to make a film...
MATT DAMON: No, not a good one [laughs]. You have to suspend that Yankee sensibility that this is costing money. When I'm on a movie set, in the back of my head is this ticker rattling off thousands of dollars every second. You have to just turn that off. There were days when we would find ourselves in the middle of a scene and realize ''This isn't in the movie!'' The great thing is, when Bourne scenes don't work, they really don't work. I did so many awful scenes that never made it into the film.

Will we get to see them on the DVD?
Never. To me, that's like walking into a room holding a pile of s--- and saying ''Look what I almost stepped in!''

There are so many locations in the film: Madrid, Morocco, London, Paris, New York...it must have been exhausting. I mean, you look tan and rested now, but in the movie you look like crap.
Yeah, well, that was two things. One, it was harder work than I've ever done because it was so unrewarding. There's a buzz you get when it's working, and we didn't really have that.

It sounds like the exact opposite of making an Ocean's movie.
Exactly. That's just fun. There were days of fun on Bourne, but a lot of it was gallows humor.

And the suits at Universal are just sitting back in L.A. thinking it's all going smoothly?
No, they know. But they're just like, ''You guys gotta figure this out.'' This movie was 140 shooting days, which is the longest movie I've ever been on. There wasn't a single day where we didn't have new pages! The main issue was that a question was never answered: Why was Bourne here? He atones for what he's done in the last movie. Presumably, he's going to go off and walk the earth like Caine from Kung Fu and that's the end of the guy. And what Paul settled on was that it has to be a story about meeting his maker.

Was it that vague when you signed on to do it?
I did the whole movie that way. In any given scene I didn't know where I'd just come from or where I was going. Which, as an actor, you kind of need! And Paul's only direction was ''Butch-er and more intense!'' Finally I was like, ''If you give me the f---ing 'butch-er and more intense' note one more time, I'm gonna kick your ass!'' It's incredible that we've been able to pull the rabbit out of the hat three times.

NEXT PAGE: ''I don't know why people like me, and I don't know if I want to know. That might be the kiss of death''