Oxygen won’t exactly rattle science fiction but it’s still satisfying for the simple story it tells.

A woman awakens in a life-preserving chamber. She has no idea how she got there. She has no memory of who she is or where she came from. Only brief flashes of her past pop into her mind. There’s little time for recollecting these thoughts, however, as the clock is ticking. Her pod is malfunctioning. Oxygen is running out and the chamber’s computer program is offering little help in escape or knowledge. So many questions pummel this frightened character forced to put the pieces together in this thrilling sci-fi bottle movie.

The computer character of M.I.L.O., seen only as a vibrating ring on a digital display that rolls on like a cousin of HAL 9000, is bound by secrecy, security, and cryptic responses. The basic questions will not be answered, where M.I.L.O. refers to the woman by her subject number. The more questions she asks, however, the closer she comes to the truth. She’s able to call outside of her pod and reach someone familiar with the pod. However, she finds that she can’t trust these people either as they keep redirecting her call and hiding information from her, pretending they don’t know who she is or how she got there. As we later learn, there’s a very good reason.

It’s hard to talk about this film without revealing the grand twist of just how this woman ended up in a chamber of rapidly depleting oxygen levels. What I can say is that it finds all the right ways to make her story an intense experience. There are many points of hopelessness where the longer the protagonist is kept in the dark, the more she starts to lose her cool about dying in such an environment. M.I.L.O. becomes a part of the danger when he attempts to force sedatives to calm her down or give a lethal injection when oxygen levels become dangerously low to save her a slow death. It’s a nerve-wracking experience that is not at all recommended for those who have anxieties about being trapped in a coffin.

The way the clues are slowly oozed out of the trapped woman’s memories in a most clever manner. Fragments of who she is start coming into focus, where images of mice in mazes and falling tree seeds on a summer day not only give her a glimpse of her past but a clue as to why she is in the chamber in the first place. Naturally, her inability to remember her past fully coupled with how in the dark she is kept about everything paints a more elaborate picture story of identity and questioning your own purpose in life. By the third act, a shocking revelation comes about that gives an eerie sensation of somber acceptance as well as a will to keep fighting for a moment of life.

My only major gripe about Oxygen is that it wraps things up almost too simply. The saving grace for the test subject comes practically out of left field and the final shot, while not bad, still bubbles with questioning the ethics of the scenario. The result is a film that leaves you with perhaps more firm answers to questions that may not all need answers. The mystery of the whole situation is what drives the edge-of-your-seat excitement and by the end of the film it feels as though the picture is all out of meaty philosophical ideas to munch on.

Oxygen won’t exactly rattle science fiction but it’s still satisfying for the simple story it tells. The performances are strong, the tension mounts wonderfully, and the special effects are not too shabby. Considering most sci-fi cinema these days relies on bigger theatrics, it’s refreshing that a film such as this comes with more ideas in its thrilling story of mystery and identity than just a bombardment of special effects and action.