“I break out of prisons for a living.” “Godzilla’s hurting people, and we don’t know why!” Now, joining that pantheon of inexplicable movie lines is Primate’s one-sentence explanation for Lucy’s (Johnny Sequoyah) wealthy family having a pet chimpanzee. Nick (Benjamin Cheng) explains to Hannah (Jessica Alexander) that Lucy’s deceased mom was “researching breakthroughs in human and chimp communication.” Can you get a degree for that at Columbia? As a cherry on top, Nick further elucidates that this woman “just brought [chimpanzee] Ben home one day.” He’s been here ever since, running around the household like a canine.

No wonder Primate devolves into grisly carnage. If you’re treating a chimp like a pet, horrific things will transpire. That’s as old an adage as “snow goons are bad news.”

Primate kicks off when college-aged Lucy returns to Hawaii and her family, sister Erin (Gia Hunter), and author father Adam (Troy Kotsur). Finals are over, and she’s looking to reconnect with her loved ones as well as best pal Kate (Victoria Wyant) and unexpected guest Hannah. Oh, and the chimpanzee Ben (Miguel Torres Umba). Can’t forget him. Adorned with a red shirt and immense intelligence, he’s a playful soul clearly enamored with his “adopted” family.

All that changes after a mongoose bites Ben, giving the great ape a serious case of rabies. With Adam on the road for a book event, Lucy and her friends have the house to themselves and are too busy partying to notice the warning signs of their once docile companion’s unraveling. It is only when Ben shows off his newfound penchant for bludgeoning people to death that the girls realize the danger. If you think outmaneuvering Ghostface or Michael Myers is hard, try evading a killer who can clamber along walls and roofs. These humans don’t have a prayer.

Lucy’s greatest struggle isn’t Ben, it’s the script. Frequently overcrowded and defaulting to tell-not-show, the screenplay by Ernest Riera and director Johannes Roberts gives the returning daughter so many underdeveloped personal subplots that none leave an impression. The most frustrating of these are long-simmering sibling issues between Lucy and Erin. With Erin not on-screen for most of the film’s second half, both the audience and the filmmakers are likely to forget all about it. And if no one is thinking about it, why introduce it in the first place?

The personal problems don’t work in concert with Ben’s expressions of disease-poisoned wrath. Without that storytelling relationship, Lucy’s concerns and motivations are muddy, and she ends up shoved to the margins. Compare this to my beloved Crawl. That creature feature’s streamlined screenplay stays firmly in tune with its protagonist’s interiority, alligator mayhem and intimate scenes working in tandem.

Primate’s weird screenwriting problems are especially exasperating as the monkey, er, ape business is far better-than-expected. This is a grimy motion picture. It isn’t afraid to go gasp-inducingly nasty with plenty of limb-shattering deaths. If you’re squeamish around skin peeling or squelching sound effects, stay far away. For fellow sickos like me, though, it will have you apprecatively whispering, “oooo, gross!”

Adrian Johnston’s score also bats way above its weight class. More than any other Primate attribute, these melodies sell the setting as an idyllic home on the edge of becoming a nightmare realm. Johnston scatters all kinds of sonic surprises throughout, particularly with the deployment of electronic noises. Who knew the Becoming Jane composer had these chops in his back pocket!

Best of all, Primate’s solid at delivering what audiences want. A cold open starts the story in media res, ensuring moviegoers experience a stalking, murderous chimpanzee from the start. Even when Roberts then jumps back 36 hours, the film supplies instances of Ben pulverizing folks at a steady clip. It’s all cheeky, gore-soaked fun that doesn’t skimp on tension or enjoyable jump scares. While few of the frights are especially memorable, they’re reasonably fun in the moment.

Roberts, happily, depicts Ben mostly through practical effects work. Realizing him tangibly rather than digitally is critical to selling the ape as a potent adversary. He constantly registers as being in the same space as these characters, rather than incessantly reminding audiences of CG shortcomings. Props, also, to Umba for his detailed work portraying Ben’s unpredictable psyche. Even in the deepest throes of rabies-induced madness, Umba’s physicality offers a flicker of Ben’s earlier, kinder persona.

Unfortunately, this level of craftsmanship is not consistent. Roberts and cinematographer Stephen Murphy’s visual aesthetic is frequently erratic. For every remarkable extended single executed with real precision, there’s frustratingly clumsy and cramped blocking.

In the pantheon of monkey/apes on the loose movies, Primate is no Better Man, but certainly more involving than Shakma. Despite an abundance of issues, not the least of which is the characters’ incessant stupidity, there’s plenty of fun. Watch it in a crowded theatre full of similarly minded sickos for maximum effect.

Primate’s stomping into theaters everywhere on January 9, 2026.

Watch Primate’s Trailer here: