Director Jon Favreau’s movieIron Man had a killer ending—Tony Stark, played by Robert Downey Jr., admits to the world that he’s the armored super-hero. And then the Black Sabbath kicks in. But coming up with a big finish isn’t enough in the world of sci-fi action. You have to have some explosions. Kill some people along the way—hopefully with a flourish or two. Genre mashups are good for that kind of inventiveness, which is why Favreau’s new movie Cowboys & Aliens has ginned up excitement in the geek community. Wired talked to the director about death and the circle of life, great endings, and the best reason to break up with a billion-dollar franchise.

Wired: You’re not going to have cowboys fighting aliens with six-shooters, are you? They’d get slaughtered.

Jon Favreau: To me, that movie would cross the line where I start to say, “OK, this is complete fantasy.” I think you want to have some degree of plausibility. We introduce an alien weapon for Jake, Daniel Craig’s character, but then we justify it through the character’s experience and the price that he has paid for having this asset. That’s something that makes sense in sci-fi, but it also makes sense in a Western. The gunfighter always pays a tremendous price for bringing salvation to the people. Shane always has to move on. Without that pathos, he’s just an action hero.

Wired: You still have Craig and Harrison Ford cheating death.

Favreau: If you aspire to a mythic structure, you see that every myth is on some level a coming-of-age story. And every coming-of-age story deals with a death and a rebirth. In both Iron Man films, there’s a death scene and Tony emerges as a different person. The challenge on Cowboys & Aliens was finding the intersection of the two genres. I felt that, at their core, both dealt a lot with death and loss. Sometimes it’s just complete arbitrary destruction, like Cloverfield or War of the Worlds. Usually it’s a metaphor for loss on some level. In Westerns, especially the more stylized, Sergio Leone version of the western town, it’s a sort of purgatory, a way station between civilization and the great unknown. So the death metaphors ring pretty loudly.

Wired: Not exactly a theme for an upbeat summer movie.

Favreau: That’s not the tone of the film, but you’re asking about it. The trick is to be able to have that under the surface yet still present the film in a way that’s appealing.

Wired: How important is the final scene of a movie? Kicking with Downey saying “I am Iron Man” was obviously memorable.

Favreau: We were trying to cut against the grain; we wanted to surprise people with the ending. And we ended up surprising them. But we also ended up giving ourselves a tremendous burden for the next film.

Wired: It seemed like you were having fun with those movies. Why aren’t you going to direct number three?

Favreau: I love the origin story of Tony Stark in the cave. The original was very small, with a small group of characters. It was set in the real world. But now we’re saying that the whole Marvel universe can exist. I think people with different sets of skills are probably better suited to deal with all of these intersecting story lines and characters. Once you get into all the other superheroes and the world starts to expand, I start to lose my footing. Even reading comics as a kid, I used to get lost when they all overlapped. I understand the rules of a Western really well—much better than I understand the rules of a superhero movie.

Wired: But you’d come back to play Tony’s sidekick Happy Hogan, right?

Favreau: Oh, sure. Of course I would.