With, for much of its running time, just one human character trapped in an isolated compound with a seemingly-friendly robot whose intentions eventually come into question, the Netflix sci-fi thriller I Am Mother has a lot in common with Duncan Jones’ Moon. Ultimately, however, the movie lets some of its thought-provoking themes and ambitions give way to standard horror tropes.

The film opens with the end of the world, though we don’t get to see it. On-screen text provides minimal details about an extinction event while we hear what sound like explosions outside the walls of an underground bunker identified as a “repopulation center.” Almost immediately, a robot body is activated and selects a human embryo, one among tens of thousands, from storage. The fetus is incubated with advanced technology and rapidly forms a baby, the last human alive on Earth.

The robot, which has a soothing voice provided by Rose Byrne, is programmed to care for and raise the child as its mother. In montage, we see the girl grow through the years into a teenager known as Daughter (Clara Rugaard). She has lived her entire life in isolation, knowing only Mother, and what Mother has taught her. She understands that humanity was wiped out in some sort of contagion, and that life can no longer exist outside the compound. She is the first test subject in a failsafe plan to preserve the species. If she survives and thrives, Mother will incubate other embryos and begin the process of restarting the human race. To that end, it’s very important that Daughter be rigorously schooled and tested to ensure that she’s smart, resourceful, and understands the complexities of ethical decision-making. She is, after all, the most important person in the world.

Mother is a kind and caring, if sometimes strict, parent. Daughter has had no reason to ever question her. That changes when she hears a banging sound coming from outside an airlock door, followed by a human voice begging to be let in. The source is a woman (Hilary Swank), and she’s injured. She’s terrified of and distrusts Mother instinctively. This event naturally upends Daughter’s world. She questions everything Mother taught her, even more so when the Woman sows seeds of doubt about what other important information Mother may have withheld from her. For her part, the Woman may also have secrets of her own.

Despite its contained setting and limited cast, I Am Mother is a very sleek and polished sci-fi picture with good performances, a compelling plot, a pretty cool robot design, and even a few ideas in its head. Unfortunately, it turns into something of a rote killer-robot-on-a-rampage flick at the end, complete with the heroine wandering through dimly-lit corridors (lights flickering for no particular reason), defending herself with an axe. I’m also not sure that all of the plot twists entirely make sense.

That may be why the movie went straight to Netflix without landing a theatrical run. However, as far as Netflix Originals go, it’s worth a watch and is more interesting than some other recent titles that got more publicity.