Around a Small Mountain travels with an itinerant one-ring circus of proud artisans, performing to shrinking rural crowds. “We’re the last classics,” announces one. And after a long and stubbornly marginal career heading his creative family, 82-year-old director Jacques Rivette nears closing time with this commedia dell’arte. Leads Sergio Castellitto and Jane Birkin have appeared for Rivette before; regular Pascal Bonitzer contributes to the script; Irina Lubtchansky, taking over the cinematographer’s chair, does proud her recently deceased father, William, Rivette’s DP for 30-odd years. The premise is skeletal: Vittorio (Castellitto), an Italian passing through the Cévennes, is waylaid by the mysterious wince in the gap-toothed smile of the troupe’s tightrope walker, Kate (Birkin). There’s a breathable air of Southern late-summer afternoons in the public squares and campgrounds where Vittorio and Kate play their approach and retreat. Rivette inserts parentheticals of performers at work, including a reprised routine by the clowns, into which Vittorio is drawn as an incompetent substitute in a keynote scene, funny and illustrative of Rivette’s improvisational practice. Rivette is known, if for nothing else, for making epically long features; this is his shortest, sidling along after the tragic secret that’s kept Kate away from performing for decades. It’s all slight enough to blow away, and rare enough to warrant seeing it before it does.