It's been a while since we've had a good "apartment-renting life is a noxious hole of atomisation and urban ennui" thriller, and 1BR , the first feature written and directed by David Marmor, does a fine job of filling that gap. The film has excellent bones: it's a story about a young woman Sarah (Nicole Brydon Bloom) whose life thus far has gone no place in particular except into sullen isolation, having the good fortune to end up in a warm, inviting community in the apartment complex she lucks into as she tries to restart her life in Los Angeles. The bad fortune accompanying it is that, in fact, the apartment community is a cult, and this offbeat new sense of belonging comes at the cost of being tortured into giving up her own free will or individuality.

That basic tension, between a lifestyle that isn't going anywhere at all and a lifestyle that offers meaning and community but is horrible and violent, underpins everything that makes 1BR work as a psychological thriller and a low-key message movie about the danger of cults. The film is very much at its best in its middle act when this is its main focus, a battle playing out behind Sarah's terrified eyes, taking advantage of the somewhat unfocused performance Bloom gave in the first act; she hasn't entirely emerged as a stable character by the time the cultists get to breaking her down, so it's more of an open question whether she has enough characterisation to withstand that.

But I have skipped ahead a bit. The film breaks neatly into three chunks, which are not quite equal to thirds. The first of these is all about innuendo and a creeping sense of horror, with Sarah finding something odd but basically sweet about the people in the apartment complex she's just landed in. The film benefits from casting that makes all of the apartment-dwellers read pretty instantly as types, especially Susan Davis as Edie Stanhope, a faded movie actor with a garrulous, grandmotherly energy, Giles Matthey as cheerful hot boy Brian, and Clayton Hoff as sad, haunted Lester. Cumulatively they, and the rest of the ensemble, make the community feel like a real, living, organic thing, without being so specific that they draw the film's center of gravity towards them. Marmor is generally very good at making them feel like we're only seeing their surfaces in these early scenes, which is an important part of how the film starts building its sense that something is awry; and this is where that first third ends up going, as Sarah grows increasingly concerned that there is something afoot in that apartment complex, though she can hardly point to what it is or how she even knows its there. It's more like an off vibe.

This is a tough thing to sustain, and ultimately, 1BR doesn't quite manage to do so; the first third is, honestly a bit draggy and almost too deliberately obtuse about where this is going (it's not even initially clear that this is a horror-thriller, notwithstanding a poster that enthusiastically gives the game away, and the fact that a title like 1BR kind of has to go with a horror-thriller). Bloom's fuzzy performance does absolutely nothing to combat that feeling, either. Only the unexpectedly harsh, overlit, washed-out cinematography by David Bolen really does all that much to push the film towards its second movement; and it does so quite well, to its credit. This film has a very weird visual aesthetic, one that's somewhat caustic and sickly, but it gets at something of the sterile brutality of the Southern California lifestyle that's ultimately the subject of all the film's commentary (the cult, which seems to most closely borrow from the New York-based NXIVM, is founded on ideas of can-do self-help bromides and post-hippie feel-goodism that feel like Los Angeles is their most natural home), and this helps prepare us for the series of sick shocks that occur during the middle third.

I will not, of course, spoil these, other than to say that Marmor does an outstanding job of staging scenes to evoke the horrible sense of anticipation that is one of the keys to how torture actually works; the film has one major violent setpiece in the middle and as appalling as the violence is itself, it's really the seconds where we see the violence is coming that are the most stomach-churning. This whole middle sequence is both the film's obvious strongest point and also its most unpleasant sequence to watch; it is, no more and no less, about the chain of psychological and physical tricks used to break down an individual as part of cult indoctrination, and while the film remains steadily non-exploitative (it has after all, only one violent setpiece during this whole sequence), its sketch of this process is vivid enough and draining enough - matched well by the bleached-out cinematography and Bloom's shell-shocked performance - that it feels constantly visceral. I do not know that 1BR passes the "I understand why I watched this" test; it convincingly suggests that cults are bad, which isn't a message that anybody who goes to the effort of watching the film is likely to find startling and new. But as a psychological thriller, watching Sarah fight with less and less vigor as she is slowly demolished, it's pretty impeccable, shattering stuff.

The film's most unexpected trick is how much of its running time is left after this part of the movie is over, and I really don't know that it came up with something to do with that running time. The last act is, by some margin, the most cluttered and sprawling (security camera timecode confirms that we're looking at several months of activity, compared to like a week for the first two acts combined), with several different plot threads all woven in for a couple of scenes at a time. Some of these work, and at least one really big development, the one that kicks us into the finale, seems to have been included solely for arbitrary reasons, like the characters themselves knew that something had to precipitate the climax. It is, at any rate, the pat of the movie that feels the most movie-ish, the least like a mood piece or a psychological sketch, and the last few minutes feel like they came from some other project entirely.

Still, that middle is up to something. "It's such a vivid depiction of torture!" is hardly a selling point, but it's handled so delicately and with such careful sympathy for Sarah's state of being, that it never feels cruel for cruelty's sake. It is, altogether, a very harrowing and evocative and involving psychological thriller - and this at least spills over into the last third - and those don't come by every day, or every month. The film as a whole is too inconsistent to come anywhere close to genre film greatness, but greatness is absolutely hiding within it.

Also check out Rob & Carrie's interview with Marmor, producer Alok Mishra, and co-star Naomi Grossman