Within the first 10 minutes of Marriage Story, we learn that the central couple—stage actor Nicole (Scarlett Johansson) and theater director Charlie (Adam Driver)—is headed toward divorce. After a sweet, sleight-of-hand opening, in which they each recount in voiceover the things they love about the other as we see quick-snippet demonstrations of those qualities, there is a hard cut to a mediator’s office. For the next two hours or so, we follow the couple’s increasingly fraught, heightened, and painful negotiations, especially as they involve their young son (Azhy Robertson). Written and directed by Noah Baumbach, Marriage Story attempts a balanced account of this dissolving relationship, even if it will be impossible to resist assigning blame as a viewer. (I was personally more convinced by Nicole’s claim—“I got smaller”—than Charlie’s insistence that his career and their marriage were always of equal importance.) Either way, Baumbach gets career-best performances from the leads. Johansson delivers that line in a bravura, single-take monologue at her lawyer’s office; Driver bursts into song at one point with a conviction that will leave you stunned. And in the movie’s big argument scene, the pair spirals from politeness to anger to hatred to regret with an ugly honesty you’ll rarely find outside of the films of John Cassavetes. With sharp supporting turns from Alan Alda, Laura Dern, and Ray Liotta, as well as the deft editing of Jennifer Lame, who has worked with Baumbach on Frances Ha, While We’re Young, Mistress America, and The Meyerowitz Stories (New and Selected).