Based on the notorious 1971 study in which a group of Stanford students pretending to be prisoners and prison guards descended into psychological abuse and brutality after barely a day, The Stanford Prison Experiment is an impressive but maybe too literal reconstruction of those events. Dr. Philip Zimbardo randomly divided twenty-four students into prisoners and guards, then left the guards in charge, with the guards, working in shifts of three, running herd on nine prisoners. The experiment was supposed to run for two weeks but was shut down on day six after Christina Maslach, who later married Zimbardo, objected to the conditions of the prisoners, which included being forced to relieve themselves in buckets, sleep deprivation, and one dude who went on a hunger strike. Zimbardo’s study has been criticized as not wholly scientific, and it’s still controversial, but it does effectively demonstrate that people are The Worst.

Written by Tim Talbott (South Park) and directed by Kyle Patrick Alvarez (C.O.G.), The Stanford Prison Experiment has a lot but also a little to work with. The psychological aspects of the film are incredibly rich, so of course the acting is top notch. Billy Crudup stars as Zimbardo, and he does a good job of showing Zimbardo’s own descent into madness as he gets swept along with his study (the real Zimbardo freely admits he became part of his own experiment), and James Wolk is great as one of Zimbardo’s assistants—he has so much presence on the screen that I cannot believe this guy can’t find better leading parts than the summer’s most batsh*t show, Zoo. But the real stand-outs are Michael Angarano as the alpha guard, and Ezra Miller as a rebellious prisoner.

Angarano has been knocking around Hollywood for a while—he’s probably best known as Kristen Stewart’s ex—but The Stanford Prison Experiment is the best showcase he’s gotten for his talent yet. There’s a stretch in the middle where Angarano holds the film together solely with his performance, as the story gets repetitive and it’s only the very real sense of menace that he brings that keeps things engaging. (I have a feeling Angarano will be one of those guys who doesn’t really hit his stride and break out until he’s around forty.) Ezra Miller, too, brings a kinetic energy to the film, and it’s no coincidence that things start to feel long and draggy once Miller checks out. Thomas Mann manages to inject a little zazz into the later part of the film as a late inductee to the experiment, but he’s not around long enough to make a significant mark.

The Stanford Prison Experiment lives and dies by the quality of the performances, because there is very little else in the film. The institutionalized look of the faux-prison is visually barren, which is the point of the experiment but makes for dead boring visuals in a film. Alvarez works hard to overcome the inherently uninteresting setting by deploying a lot of different camerawork, from tracking shots that reference Stanley Kubrick—apt for the 1970s setting—to slow motion to random close-ups, but ultimately we spend two hours staring at the same hallway, and there is just no getting past how tedious that gets.

Likewise, the script, which does offer some really great interactions, gets bogged down in the repetitive nature of the story. There’s real elegance in The Stanford Prison Experiment, but it is kind of a problem when less than twenty minutes in, as the first violence breaks out, one character says, “This is where it’s going,” and you think, “Yeah, I get it,” and then you spend the next hour and forty minutes reinforcing the thing you already get. On a meta level it’s kind of acceptable since it reinforces that Zimbardo should have seen the writing on the wall and shut it down right then, but within the film, you can’t escape the NO DUH aspect of the story. Usually two hours is not too long, but with this film it becomes something of an endurance test. Which, yes, there is a larger real-life connection between story and subject, but that doesn’t change the fact that the film feels longer than it is. But this is truly an actor’s piece, and The Stanford Prison Experiment is worth it for Miller and Angarano alone.