Early in The Breach, the new horror film from Rodrigo Gudiño, a body turns up on the Porcupine River and a driving, powerful riff kicks in: It’s the sound of the film’s executive producer and composer making his presence known. Before he was Slash, the legendary guitarist of Guns N’ Roses, he was Saul Hudson, a kid who loved horror.

“I’ve been hustling, you know, trying to produce movies, since the last one that I did, which was all the way back in 2013,” Slash says.

The Breach stars Emily Alatalo, Natalie Brown, Allan Hawco and Mary Antonini. Based on the book by Nick Cutter and adapted by Ian Weir, the story begins when the mutilated body of a physicist washes up on the shores of the river. Police chief John Hawkins (Hawco) must work with his ex-girlfriend Meg Fulbright (Alatalo) to make sense of the secrets that lie within the walls of the physicist’s eerie home, which is haunted by something sinister.

Gudiño pulled Slash onto the project knowing he was a fan of horror.

“I’m an old-school sort of horror fan,” Slash says. “We’ve been using Lovecraftian kind of references on this, but it definitely has sort of a slow burn, sort of 70s aesthetic, and there was a suspense thing because you really don’t know what the fuck is going on until the last act. It’s the kind of thing where, for me, it’s more cerebral than it is just everything, you know, spilled out onto the screen. He knows my style, so he knew I would dig it.”

In the past, the rock star has scored films including 2013’s Nothing Left to Fear, 2011’s This Is Not a Movie. He also contributed music to Quentin Tarantino’s 1997 crime drama Jackie Brown. Slash worked with composer Aybars Altay to score The Breach.

“We went back and forth taking this particular melody that I had and making it really ominous and heavy for the intro. But then for the other parts throughout the movie that I did, everything just seemed to work on acoustic — very sparse and sort of naked,” he said.

Slash doesn’t let his reputation as a hard rock guitarist pigeonhole him into a certain genre when it comes to film scores.

“Being that I’m a guitar player and sort of recognized for doing sort of loud, boisterous, hard rock stuff, that does not hardly ever apply when I’m writing something for a movie,” he said. “Usually, every script I’ve written sort of pulls me in another direction. That being said, you can have a rock song in a movie, and that’s great. But as far as the actual score is concerned, it can be something that’s super, super light, or it can be a lot of you know, stand-up bass and cello.”

He says when it comes to scoring a movie, the key is to “follow your gut instinct.”

“I can’t be bothered with whatever people’s expectations are. I mean, the variables in that alone would make you crazy, if you start thinking really about what other people’s expectations are going to be,” he said. “You just have to sort of just follow your gut instinct, and then once you’ve established that, you can think, Now, is that going to make sense to anybody else listening, or not? But even then, I don’t really — I just do what I think is going to work and what sounds good to me, and then just go from there. I always have done.”