This is a strange one, a police procedural-type of story mixed with an almost Gothic, Hammer-esque sensibility. It mostly works, but the two strands don't entirely mesh. The police investigation aspect is the stronger. Melanie Laurent is an intuitive detective (with twin infants at home) investigating two kidnappings that may be related. The first has ended badly (not a spoiler, this is in the opening minutes of the film) due to a hit-and-run accident that killed a man trying to deliver a ransom. The accidental killers hide the body and take the money; how they react to this provides an ongoing subplot.
Once the identity of the kidnapper(s) is revealed, the film takes a detour into Gothic-y, almost Cronenberg territory. In addition, there are several flashbacks that hint at a dark past which informs Laurent's character. (I'm guessing that the novel this is based on fills in more detail about this; in the film it remains a bit vague.) The florid nature of the last 45 minutes sits uneasily with the mostly gripping procedural narrative up to that point. It's not a fatal flaw, but once we enter the world and mindset of the kidnapper(s) the film flirts with being too wiggy for its own good. However, the plotting and pacing are strong, the performances are good, the cinematography matches the dark and heightened tone of the story, and Melanie Laurent (if you ignore that at age 24, it's a stretch that she's already made detective) anchors it all as a believable and likable heroine. Plausibility is strained, but it's never boring.
