The Soul Eater (Le mangeur d'âmes)

 Elizabeth (Virgine Ledoyen) is a mannered, gives-no-fucks police inspector investigating a bizarre double-homicide in the French Alps; Franck (Paul Hamy) is an intense, driven young Captain who's on the trail of some missing children (he's introduced screaming while jogging himself ragged, which is blatant film language to let us know he's troubled.)

 Together, they fight crime. Kind of.

 The Soul Eater is a sort of collage of detective media from the last couple of decades, a film built almost entirely from common places, plot holes and contrivances tied together by a mystery that only gets shittier as the movie unspools its unlikely tangle of elements. It also throws in a possible supernatural threat and a few Nordic Noir-style disturbing plot elements to try and spice things up, which only makes its half-assed-ness feel tackier.

 It's never able to shake off the feeling that you've watched it before, but for a while it works; Both protagonists are fun to watch and, the investigation at first seems interesting. Directors Alexandre Bustillo and Julien Maury know their way around a production of this sort and provide some good atmosphere.

 The two investigators' cases (the child abductions and the double murder) are linked, of course, and they soon learn of a local folkloric figure - the titular Soul Eater - who gets a shitty rhyme to say how he comes out of the woods to eat people and leave behind evil doppelgangers or something.
 There's also a mysterious motorcycle rider, a plane crash in the woods that keeps being brought up, and more police incompetence than you can shake one of those weird little wooden soul eater totems that keep popping up at crime scenes at. And yes, more people soon start showing up dead all over the sleepy town.

 The French, of course, are adept at taking Hollywood crime movie conventions and making them their own - or at least making a banger out of them. The clearest influence here is 2000's banger The Purple Rivers (the directors have admitted as much). But there's not enough of anything here to sustain interest; the style is mostly subdued, there's very little action, and the police procedural/mystery elements hinge on people missing the obvious and other contrivances; The script, by Annelyse Batrel and Ludovic Lefebvre, adapting a novel by Alexis Laipsker, is a complete mess.

 Bustillo and Maury have ever been reliable providers of genre thrills, but while their gorehound sensibilities do give this one a welcome spike of nastiness (the only time the film comes alive is a nasty, bloody late-movie portrayal of the first crime), there's not much they can do here other than keeping things atmospheric. There are a couple of perfunctory foot chases, a couple shootings and a pretty neat car/bike stunt, but other than that everything here relies on the mystery itself -and its resolution- to hold things together... a task at which it fails, miserably.