Your new film, “The Counselor,” stars Michael Fassbender as a lawyer who gets in over his head on a huge drug deal. It’s pretty harrowing.

There’s a deep sense of stress that starts about halfway through, and you can’t put your finger on why. When you’re reading the script, it’s like there’s a series of cogs in a very clever clock. The cogs start to engage and — a good word is dread. And the dread sets in, and it stays there.

The script is by Cormac McCarthy. Anyone who’s familiar with his writing shouldn’t find the brutal tone of this film too surprising.

It’s relentless. I think he writes the truth. Because life is like that most of the time in some shape or form, whether it’s illness or the end of the world. Cormac’s a writer’s writer. You read his writing and think, I can do that, and then you sit down and try. And you try, dude.

He doesn’t seem like a screenwriter who’d welcome a lot of studio notes.

Reading this script — it was so fast and precise and crystal clear. I sat for a moment and then picked up the phone and called up the relevant person and said, “Get me a meeting with Cormac A.S.A.P.” That was Friday. I met him on a Monday, I think, in Albuquerque. We sat for about four hours in a hotel and we just chatted. And at the end of it, Cormac says, “Shall we?” And I said, “Yeah, we should.”

As a director, do you ever feel jealous of a novelist, who is able to work with no interference?

No, because most novelists are desperate to do what I do.