The renowned psychologist Kelvin, portrayed by Donatas Banionis, is sent to a space station to look into the death of one of three scientists stationed on the surface of an isolated moon. When he gets there, he finds that only two of the original eighty-plus crew members remain at the somewhat dilapidated facility: Snaut, played by Jüri Järvet, and Sartorius, portrayed by Anatoliy Solonitsyn. Their reception is strange, to say the least, and soon he begins experiencing dreams. These visions become increasingly detailed and lifelike, featuring his late wife Khari, brought to life by Natalya Bondarenchuk. Are these simply figments of his imagination or something more? Could they be genuine? Perhaps they exist in another reality? Is it a problem with the water supply? Andrei Tarkovsky uses dialogue sparingly while tightly controlling this mystery. Details are revealed gradually—sometimes conflicting, sometimes uncertain—just as Kelvin receives them, leaving us just as perplexed as he is. It’s reminiscent of a groundhog day situation that repeats itself endlessly, but he can't decide whether to escape it, change it, or continue living through it, and his coworkers don’t offer much assistance since they have been suffering from the same issues for quite some time. I won’t pretend that it doesn’t move slowly at times; the Artemyev score isn't always helpful, and the rhythm feels a little unsteady as we try to understand what's going on. However, once you get past that, this is a thoughtful exploration of how the human mind might function under stress, demonstrating just how much more there is beyond our comprehension. Experiencing it on a large screen would be beneficial, primarily to emphasize the scope of both the production and its ideas.

Source on TMDB