This is part of a mini Robert Altman season at the Prince Charles. Full details here.
Chicago Reader review:
Robert Altman's antiheroic rewrite of Raymond Chandler. Elliott Gould plays Marlowe as a chain-smoking nebbish—an innocent child of the 40s set down in what Altman sees (problematically) as the grown-up, shades-of-gray world of the 70s. The film is so inventive in its situations and humor that its shortcomings—the blunt ideas at its core—don't become apparent before several viewings. Somewhere deep down inside, there's a screenplay by Leigh Brackett (The Big Sleep, Rio Bravo); Altman has lost it in his improvisation, but it does give this 1973 film a firm, classical shape that eludes his other work. With Sterling Hayden, Mark Rydell, and Nina Van Pallandt.
Here is the trailer.