See the cover reveal for David Koepp's sci-fi horror thriller Cold Storage

Just because we defeated something decades ago doesn’t mean it is gone forever.

In David Koepp’s new thriller Cold Storage (out Sept. 3), a fast-moving, mutating fungus that fell to Earth on a crashing satellite is dealt with swiftly in 1987 after consuming a small Australian town, but rather than destroy it completely, part of the organism was locked away in a government facility.

Thirty-some years later, the lethal, voracious spore is unleashed again, and Roberto Diaz, the same man who contained it the first time, has to help a pair of trapped security guards eradicate it again before it spreads — and destroys — the outside world.

“One of the scariest things to me is not necessarily getting eaten by a monster, or getting chased down and killed by a monster,” Koepp tells EW. “The scarier thing is the monster turning me into it. That’s what’s really terrifying. I think of 1956’s Invasion of the Body Snatchers, which was probably my favorite movie of all time because it’s just so perfect and terrifying. Obviously, that one had social relevance as well as just horror.”

The hero of Cold Storage was literally inspired by someone Koepp passed on the street. “It was August. You know those nasty humid New York days? And there was a guy walking toward me who was maybe 24 and Hispanic, and he was wearing a private security uniform,” Koepp says. “He was either going to work or coming from work and he f–king hated it. Maybe I was reading that into his face, but the vibe coming off of that guy was that he was dragging himself to a job he hated.”

That gruff, workaday dedication was something Koepp wanted to throw at an alien spore that turns human beings inside out. “I thought, I want something terrible to happen to that guy at work, and he follows it through because, yes, it’s a sh–ty job, but it’s his job.”

Cold Storage is the first novel from Koepp, the veteran screenwriter of such movies as 1993’s Jurassic Park, 1992’s original Mission: Impossible, 2002’s Spider-Man, and 2005’s War of the Worlds. He’s also the writer-director of The Trigger Effect, Stir of Echoes, and the upcoming horror mysteryYou Should Have Left.

The cover for the book had to express a lot in a single image. “I’ve always felt that it’s sci-fi horror. It’s science fiction, and it’s scary, but it’s plotted very much like a thriller, so how can you say all that?” Koepp asks.

“I feel like they really did. There’s a guy in a hazmat suit, and that mist that we’re unsure about, but we’re pretty sure it’s bad. And then the guy in a hazmat suit has a gun. Without that, I feel like it’s just, ‘Oh, it’s a virus book,’ but that adds another element. It asks a lot of questions that I would like the answers to.”

Cold Storage began as a screenplay idea, but — much like its own monster (known as a “hyper-aggressive extremophile”) — the treatment outline began to grow rapidly and spread beyond the confines of a movie.

“I realized, ugh, this can’t be a treatment. You can’t write what people are thinking and feeling, that’s not allowed in movies,” Koepp says. “Then I thought, well maybe I’ll just keep going, maybe it’s a short story. And then I kept going, maybe it’s a novella. And then, after a hundred pages, I thought, maybe it’s a book.”

He was right, sort of. The novel was quickly purchased by Ecco and Harper Collins, but … it’s also going to be a movie. Paramount has the rights to that. Koepp will adapt the screenplay himself and co-produce with Gavin Polone (Zombieland, Curb Your Enthusiasm.)

“I would never want to direct it, in part because it just needs someone else, and because that would just be too … like God, how much do you want to live with one idea?”

As he said before, you don’t want to be taken over completely.