For the first seventy or so minutes of Longlegs, the new film from writer-director Osgood Perkins (The Blackcoat’s Daughter), it’s a successful riff on the darker entries in David Fincher’s filmography. It channels the likes of Seven, Zodiac and the Netflix series Mindhunter into something not quite new, but different enough from its influences to keep an audience engaged. An obsessed FBI agent hunts a deranged serial killer who’s creating a mythology that only he and the agent seem to understand. We’ve been exploring these tropes for nearly forty years since Will Graham was first on the trail of Hannibal Lektor (the spelling changed in future films) in Michael Mann’s 1986 crime masterpiece Manhunter.

After spending considerable time building its gritty, bleak version of reality, Longlegs veers into the supernatural. That’s not a totally unexpected twist nor is it a spoiler because every trailer and every piece of marketing is selling the film as a horror movie. It also stars modern day scream queen Maika Monroe (It Follows, Watcher) as the FBI agent who’s tuned into Longlegs’ psychotic wavelength.

Longlegs presents itself as a mystery for the majority of its runtime, a puzzle to be solved by its investigator and by its audience. The film is set in the 1990’s, and Longlegs has been killing since the ‘70s. How does someone commit these crimes in this fashion for so long when he doesn’t seem to be present for the actual murders? I know the locked-room mystery enthusiasts out there are salivating at this prospect, and all I’ll say here is: don’t get too excited. The answer is a nothing burger, as is the final forty minutes or so of the film.

This isn’t a case of stay in your cinematic lane nor is it an overall ill-advised genre mash-up. Crime films with occult overtones have been around since before Edward Woodward’s Sergeant Howie ran afoul of a cult in the folk horror classic The Wicker Man (1973). The problem is the film’s descent into the occult muddies the narrative. The crisp, clean lines of the story become more and more convoluted as the third act of the film progresses. The supernatural elements feel like an excuse for why the film flies of its rails before the credits roll.

Maika Monroe delivers a solid, though largely one-dimensional, performance as the dogged Agent Harker who (despite being inexperienced in such matters) makes more headway in the Longlegs case than any agent that’s come before her. Her character feels (intentionally) at a remove from the action unfolding around her as if she’s simply an observer and not a participant. I wondered more than once if Monroe was portraying Harker as someone with autism or some type of spectrum disorder (though no mention is ever made of this). Her performance reminded me of Swedish actress Sofia Helin who played an autistic detective in the foreign crime series Bron/Broen (The Bridge).

It’s nice to see Blair Underwood as Harker’s boss who has the good sense to ride her coattails to their suspect. He has the thankless “bureaucrat” role in the film, but injects his character with humor and humanity. Underwood has always been an effortlessly charming screen presence and proves that once again here. Nicholas Cage gives a surprisingly well-modulated performance as the titular serial killer. His occasional histrionics are appropriate to the tone of the film and never tip into camp territory.

Osgood Perkins is clearly a talented filmmaker. Longlegs has the grainy shot-on-film look of a grindhouse crime film. Even its shifting aspect ratios for flashbacks (a technique that’s been used and abused of late) works within the time capsule of this story. It’s a well-made crime/horror thriller that simply loses its way in the thicket of ideas that Perkins wants to explore in his 100-minute film.

When that happens, the screenplay is usually to blame. Like most films in this genre, you need to suspend your disbelief, but the film does begin with its own internal logic in place. Eventually each answer provided by the story breeds multiple new questions that are never addressed. Even the one big “twist” that arrives mid-film left me wondering if they were really presenting the development as a twist. It seemed obvious from the earliest moments of the film.

In the end, the mystery itself isn’t much of a mystery. Dust off your Scooby Doo crime-solving skills, and unmasking the person assisting Longlegs is painfully easy. As far as the supernatural angle is concerned, you just need to remember the warning provided by country superstar Waylon Jennings in 1973: “The devil made me do it the first time, the second time I done it on my own.”