Sam Bell is an ordinary guy. Finishing out the final weeks of a 3-year mining expedition on the surface of the moon, he ticks off the days by drawing smiley-faces on the bathroom wall. There are few creature comforts here: A few messages home to his wife, reruns of Bewitched, and the company of the strange robot, GERTY (voiced by Kevin Spacey), who bears a remarkable resemblance to HAL 9000, speaks in glacial tones, and all but runs the outpost.

But Sam is also dangerously close to succumbing to cabin fever: his skin carries a deadly pallor, his teeth have gone yellow, and he begins to…see things. One night (or is it day?), Sam takes the rover out to fix a downed excavator and has an accident. He wakes up in the infirmary. GERTY stares down at him with a single, cold blinking eye. What happened, Sam asks? GERTY is ambiguous. And then a stranger shows up. Is it a hallucination? Has Sam finally gone off the deep end?

Ok, here is where I stop. Go ahead, yell at me; I don’t care.  I know you want to. But better that I skirt around what happens in Moon, than spill it all and destroy the experience.

I can say that, in a way, there are two versions of Sam, both played by Sam Rockwell as completely unique identities: one is aloof and and curt, his temper hidden for a time, until a dire situation brings it violently to the forefront; the other is “a lover, not a fighter,” a passive mouse who wants only to go home to see his wife and daughter. The conflict between these two men is at the heart of Moon, and the gathering tension is only exacerbated by the loneliness and claustrophobia of their surroundings.

And what surroundings they are! The lunar surface is grey and pitted, vast and flat.  The contrast of the outpost, with its stark white walls and harsh lighting, is of little consolation to Sam. This is a deathly place. And everywhere Sam goes, GERTY follows, its long arm extended from a track in the ceiling, ostensibly to help, though we’re sure its motives are less pure than that. If anyone is to go mad, surely it is in a place like this.

Speaking of HAL 9000, if all of this sounds like it might be familiar, it is: Certainly, Moon owes more than a debt of gratitude to Kubrick’s 2001, from the dubious robot playing God, to the abstract shots of the icy-white interiors. Sam’s sense of isolation, indeed his entire character, could be said to have been modeled after Keir Dullea’s Dave Bowman. I don’t know if this is true or not, but I can’t imagine director Duncan Jones and writer Nathan Parker didn’t at least consider Kubrick’s classic as a model; the coincidence would just be too great.

Still, this is a very good film, despite its similarities to a much better one. Moon ultimately poses some tough ethical questions, which are handled subtly, rather than forced on the audience with the weight of a sledgehammer. And Sam Rockwell proves, yet again, why he is one of the best and most reliable actors working today. Playing two versions of the same character can’t be an easy task, I’m sure, but Rockwell does it convincingly.