Imagine pitching an idea to a major studio based on a vague dream about the desert and identity theft — and they go for it. That’s pretty much how Robert Altman came to make this oddball drama, which says a lot about filmmaking in the gutsy (or crazy), auteur-driven ’70s. A serenely terrific Duvall plays a delusional loner, and Spacek is the mysterious waif who latches onto her. Janice Rule, as a pregnant artist with a lout for a husband, floats on the periphery until the end when…well, it’s not entirely clear what happens. EXTRAS And don’t expect Altman to explain all. His captivatingly articulate commentary expounds upon script assemblage, the art of acting and cinematography, and his disciplined use of accident and improvisation. (Plus fun stuff like the time Spacek barfed after guzzling a big mug of beer for a scene.) As for the deeper meanings of his hypnotic but ultimately unsatisfying phantom of a movie, he leaves that up to us to decipher.