I'm often asked about Kay Lenz and in which role did she look her best. While the answer to that question is not clear (and would probably not be the same for everyone), a great candidate would be The Passage.
The 1979 film was not well received upon it's release and was subsequently relegated to the realm of obscurity. Somewhat recently, however, The Passage has been re-released and is available for any and all armchair critics to review and pass judgement over. The good news is that the movie is excellent! Of course, Malcolm McDowell is the real star here and he gives one of his best, most over the top performances as an obsessed Nazi chasing after a Basque shepherd and the family of an anti-Nazi man. And while there are a bunch of other famous people in the movie (Anthony Quinn, James Mason, Patricia Neal, Michael Lonsdale, etc), Kay Lenz holds her own amongst the parade of stars.
Kay Lenz really doesn't speak that much in The Passage but her presence is powerful. Her hair is long and flowing and her expressions are beautiful and full of meaning. One of the reasons that the film is famous is for her prolonged degradation scene with Malcolm McDowell and it is quite true that a lesser actress could not have pulled it off as well as she manages to.