On the road and off her meds, the mentally disturbed Renee LeBlanc is the subject of her son Jonathan's second semidocumentary about her deterioration.

The first, the prizewinning "Tarnation" (2004), concentrated on Jonathan's lifelong coming-out process, illustrated through Super 8 home movies and photographs. "Walk Away Renee," as the title suggests, focuses on her exasperating talent for cutting herself off from him.

Through it all, however, they remain best friends — as long as her supply of Lithium doesn't run out. She sometimes slams the door and makes devastating threats; he sometimes grows panicky, wondering if he isn't living a nightmare.

On the verge of wiping out his savings as he moves Renee from Houston to New York, Jonathan does his best to deal with several family crises. The catalog of horrors occasionally feels incomplete (who's holding the camera in the most intimate scenes?), but the movie does an exceptional job of expanding on its narrow focus.

John Hartl: johnhartl@yahoo.com