László Nemes's Son of Saul is the stuff of nightmares. (That's a compliment.) At the Auschwitz-Birkenau concentration-extermination camp, Saul (Géza Röhrig) is part of the Sonderkommando, prisoners who were forced to assist with the mass slaughters. Convinced that a boy who briefly survived the gas chamber — and is subsequently killed so his body can be examined — is his son, Saul sets out to find a rabbi who'll perform a proper burial, while all around him, conspirators plot the real-life prisoner uprising of Oct. 7, 1944. Whether the boy truly is his son is irrelevant, because Son of Saulis less about the narrative and more about what Saul himself sees and hears and endures. There are comparatively few edits, and Röhrig is almost always in the narrow 1:1 frame, often shot from behind. He never quite fills it — the horror is always lurking around the edges — although we hear far more than we see, and the sound design is almost more important than the visuals. In those respects, Son of Saulhas similarities to Alejandro González Iñarritú's The Revenant (another compliment). While the former is claustrophobic where the latter is expansive, both are about lone men traveling through Hell on impossible quests. They have little chance of finding redemption, but it wouldn't really be Hell otherwise.