The passionate clarity with which she asserts her views is persuasive, and her complicated charisma makes her an irresistible, unforgettable screen presence. Barrese shoots her at home and outdoors, in front of a classroom and in conference with students. She smokes, vapes, makes coffee and dances. At London Fashion Week, she appears on the catwalk, holding her own with much younger models. Her old friend Lauren Hutton stops by for a visit. (Barrese is banished for most of it.) In some scenes, Barzini seems heartbreakingly fragile, in others indomitable.

Growing to like her — and also, maybe, to be a little afraid of her — the viewer is trapped in a further contradiction. To embrace this movie fully means to accept the case for its nonexistence. At the very least, it’s impossible to watch “The Disappearance of My Mother” without a measure of ambivalence. Gratitude for the chance to make Barzini’s acquaintance, and for Barrese’s sensitivity in making the introduction, is accompanied by ethical queasiness.

That is very much the point. Barzini’s critique of the culture of glamour and consumption is not easily refuted, but it is nonetheless partly undermined by her own magnetism. Footage and photographs from her earlier life cast an inevitable spell, as does Barrese’s decision to “cast” young models as versions of his mother. The film opens with screen tests during which these women apply makeup to replicate the grain de beauté that is one of Barzini’s distinguishing rates. Later, they read passages from a memoir in which she recalls her unhappy, wealthy childhood and her subsequent career.

This is not “the biography of my mother.” Those unfamiliar with Barzini’s life might consult an interview conducted by one of her nieces and published earlier this decade in Document Magazine. It provides information about her family and her political views that is missing from Barrese’s film, which is more about his mother’s human presence than her history and accomplishments.