Rightly described by Dave Kehr as Jacques Rivette’s “breakthrough film, the first of his features to employ extreme length (252 minutes), a high degree of improvisation, and a formal contrast between film and theater,” this rarely screened 1968 masterpiece is one of the great French films of its era. It centers on rehearsals for a production of Racine’s Andromaque and the doomed yet passionate relationship between the director (Jean-Pierre Kalfon) and his actress wife (Bulle Ogier, in her finest performance), who leaves the production at the start of the film and then festers in paranoid isolation. The rehearsals, filmed by Rivette (in 35-millimeter) and TV documentarist Andre S. Labarthe (in 16), are real, and the relationship between Kalfon and Ogier is fictional, but this only begins to describe the powerful interfacing of life and art that takes place over the film’s hypnotic, epic unfolding; watching this is a life experience as much as a film experience. In French with subtitles. a Sat 5/19, 3 PM, and Thu 5/24, 6 PM, Gene Siskel Film Center.