Director Johannes Roberts, known for his work on The Strangers: Prey At Night, returns to the horror genre with a spine-tingling new film.

Primate, now showing in theaters, tells the story of a family’s idyllic tropical getaway that takes a dark turn. Their vacation descends into chaos when Lucy, played by Johnny Sequoyah of Dexter: New Blood fame, witnesses her brother—who happens to be a chimpanzee named Ben—contract rabies and embark on a terrifying rampage.

Roberts collaborated on the screenplay with Ernest Riera, bringing together a cast that includes Jessica Alexander and Oscar-winner Troy Kotsur.

The film’s intriguing plot, combining elements of horror and camp, has captured audiences’ attention. It’s already drawing positive reviews, boasting a 77% rating on Rotten Tomatoes.

Despite its gripping narrative, Primate isn’t rooted in reality. Notably, the role of Ben wasn’t portrayed by an actual chimpanzee. Actor Miguel Torres Umba took on the part, utilizing prosthetics and puppetry to convincingly bring the character to life.

Here is everything we know about what inspired Primate.

Is Primate based on a true story?

Primate is not based on a true story. But there have been several reports over the years of people being mauled and viciously attacked by their beloved pet chimpanzees.

In one incident in 2009, Charla Nash was attacked and blinded by her friend’s pet chimpanzee, Travis. The animal mauled her face, ripping off her hands, eyes, eyelids, nose, and began eating her, according to People. Nash underwent a face transplant and is reportedly planning to undergo a double hand transplant.

Roberts said Stephen King’s 1981 novel Cujo (and the 1983 movie adaptation) strongly inspired him to write the movie.

“I’m a massive, massive Stephen King fan, and a massive fan of Cujo,” he said, per Polygon.

But why chimps?

“It just seemed like a really, really unpleasant idea,” Roberts said. “A dog, you kind of feel a sympathy with. But chimpanzees? I just think they’re scary. […] Dogs are one thing, but chimpanzees are little fucking shits.”

Primate is playing now in theaters.