Less than thrilling thriller with some ideas

Rating: 8/10 (18 February 2017)

Three girls, among them two popular ones and one social awkward one, are kidnapped by some guy and put in a room in a cellar. He's a clean-freak. Then the same guy shows up but this time with the personality of a little boy, at another time with the personality of a strict woman. We also see him as he visits his therapist with the personality of a fashion designer.
The girls try to escape so the guy separates them. The socially awkward girl, Casey, turns out to be the leader. In flashbacks we learn that her dad and uncle were hunters and for some reason took her hunting and taught her when she was very little. The uncle also apparently abused her physically and sexually.
There are some more visits to the therapist, who can tell something is going on because she gets several emails from the guy requesting emergency meetings, but the fashion designer who shows up claims nothing is going on. Apparently one of these personalities had an issue with girls in underwear and by now the three girls are almost in underwear.
The girls continue to meet with the various personalities who start warning about the coming of "the beast." The therapist, too, realizes she isn't really in the presence of the fashion designer but in the presence of the kidnapper/strict guy, who also starts announcing the coming of the beast.
The girls start again working on their escape, the therapist visits the guy's lair, and around this time the beast arrives. We also learn the fate of the girls.
Split, as the trailer revealed is obviously about a guy with dissociative identity disorder with more than 20 personalities. We only meet a couple of them. While we learn with the girls what is going on the movie is very exciting. Once we know what is happening, the movie loses quite a bit of steam. The announcement of the arrival of the beast isn't nearly as effective as it should be. It reminded me a bit of the more powerful Red Dragon, which benefited from a process of transformation as opposed to the sudden arrival of the beast.
More interesting are the therapy sessions which I take it are based on science. The psychiatrist refers to one personality coming to the fore as being "in the light." Her thinking through the situation and figuring things out is fascinating. She also offers interesting advice to Casey on how to take control of the situation if things go out of hand.
But so what? What do make of all this? The patient/kidnapper announces the beast in a Nietzschean framework of the superman. Interestingly, the psychiatrist also wonders whether a pathology such DID should be understood as potential and not just disability. Split goes beyond just the "super" in superman and considers the often neglected flipside, in this case, the pain and suffering required to achieve transcendence. On the one hand we have then the usual and tired 'you can be anything you set your mind- message. Oddly enough it results nevertheless in nothing but standard establishment puppets who won't dare question conventional wisdom and who put money and work ahead of everything else, including life. But here the beast also emphasizes vulnerability and weaknesses, or perhaps even the superman in the service of the weak. The setting of this movie beneath a zoo is also suggestive.
Split doesn't quite deliver the excitement it promises but does offer some subtle ideas.