Director Tony Gilroy has been linked to the Bourne franchise since its inception — he wrote the screenplays for the first three movies featuring Matt Damon as Jason Bourne. After the billion-dollar trilogy ended five years ago, Gilroy was busy directing his first film, Michael Clayton, which earned seven Oscar nomination. He was long past Bourne when producers came calling in 2010. After all, the franchise had already been through two directors (Doug Limon and Paul Greengrass). But what started as a simple ‘what if?” conversation soon became The Bourne Legacy — a spin-off years in the making. Gilroy phoned TIME to talk about the movie he was compelled to make, the Bourne mythology and crazy CIA operation names that didn’t make the cut.
TIME: Why did you sign on to do another Bourne film?
Tony Gilroy: I really backed into this in such a weird way. I never had any intention of ever coming back to this realm at all—much less write it, much less direct it. Then I started a really casual conversation about what we could do in a post-Jason Bourne setting. I was only supposed to come in for two weeks, but the character we came up with, Aaron Cross, was so compelling.
Rumor has it you hadn’t even seen The Bourne Ultimatum until you were in talks for a fourth film.
It’s true. After the initial conversation with producers, I said, ‘I’ll go look at Ultimatum, and if there’s anything that occurs to me, I’ll get back to you.’ And I watched it, then I called my brother Dan. I said, ‘The only thing you could do is sort of pull back the curtain and say there’s a much bigger conspiracy.’ So we had to deal with what happened in Ultimatum as the starting point of this film. Ultimatum plays in the shadows of Legacy for the first 15 minutes — they overlap.
Were you always set on Jeremy Renner as your lead?
No, Jeremy was not available to us originally. We were casting for some months, and he was never on any of our available lists. He was off-limits. And then, far through the process, when we were getting right up to the moment of desperation, all of a sudden, Avengers pulled their schedule together and all of a sudden he was free. And that’s when [producer] Frank Marshall and I went over to Germany to talk to him right away.
(MORE: 9 Spy Secrets Jason Bourne Could Teach Legacy’s Aaron Cross)
How would you compare Aaron Cross to Jason Bourne? Cross doesn’t have amnesia. He’s not an assassin. There’s chemical enhancement at play…
Obviously everybody in all these government programs can kick ass. But the new Outcome agents are required to have a pretty high level of social engineering. I mean, they’re very nimble. They have really quick minds—curious, the ability to blend in and to adapt. They have some very different problems. Jason Bourne’s problem—whether it’s from a side effect from the training or traumatic experiences—he has amnesia. He has no idea who he is. He just always searches for his identity. Aaron Cross knows exactly who he is and he knows exactly where he came from, and he tries very hard to maintain that identity.
How did the production of Legacy compare with making the first three films?
In terms of how far we go and where we go and the way we go, our film is more epic. It’s a wider canvas. We have a lot more production design in this film than in the previous films. The scope is so much larger. We shot in Korea, New York, Canada, Manila. You see how many credits there are at the end of the movie—it’s like a six-and-a-half minute crawl of all the people involved. It’s astonishing.
(READ: Richard Corliss on The Bourne Ultimatum as macho fantasy)
When looking back at the other Bourne movies—did you take anything from Ludlum or Greengrass? For the first few seconds of the movie there’s some shaky camera action—a Greengrass signature.
We were very rigorous in figuring out what had been done before. We were students of the previous films, but we knew we were doing a larger movie with this bigger landscape and this concept of pulling back the curtain on the Bourne mythology. We have a slightly different visual vocabulary, but there’s a lot of places where we really had to kick ass. We really had to move to get it to look the way we wanted.
How did you come up with the name of the CIA operations? First there was Treadstone, then Blackbriar. The Bourne Legacy features Operation Outcome…
I spend a lot of time in a sort of free state when I’m writing in the beginning and sketching. When you’re in that phase you try to make sure you’re at your desk long enough—whether it’s a couple of days or the week or the month. So when you’re really swinging and really going loose, stuff really comes quickly. I probably have a hundred pages of notes of all kinds of things that didn’t make it in here and all kinds of lists of names and programs. Some of them became side programs in Legacy: Emerald Lake and Larx are in there.
(READ: How the Bourne Boys Keep It Real)
What’s next for the Bourne franchise?
I spent two years making Legacy. All I know is I need a vacation. I want to take a break and rest my eyes, and see what it is I want to be doing when I get back. But the franchise could go on indefinitely. I mean hopefully in a non-greedy way. We didn’t wanna be asking you to buy another ticket on the way out of the theater. But it could go on.
The Bourne Legacy opens Aug. 10.