Starring Inés Efron and Ricardo Darí­n. In Spanish with English subtitles. Unrated. Plays Friday to Tuesday, June 13 to 17, and Thursday, June 18, at the Vancity Theatre

The chromosomal formula of the title refers to gender assignment, or the ambiguity of such a notion, as it is explored in this probing and provocative film from Argentina.

The offbeat tale centres on Alex (the extraordinary young Inés Efron), daughter of an intelligent urban couple that has spirited her from Buenos Aires to a remote seaside town in Uruguay. The almost feral 15-year-old may look like a girl but she has the aggressive qualities—and some key equipment—of a boy.

Played with quiet intensity by Ricardo Darí­n—the Marcello Mastroianni of Argentine cinema—Alex’s father is a marine biologist whose scientific demeanour belies a temper as reactive as anyone he is trying to avoid. It’s even harder to read his wife (Valeria Bertuccelli), who has invited some intruders into their sea-turtle nest. Her old friend (Carolina Pelleritti) is accompanied by a macho husband (Germán Palacios), who just happens to be a top plastic surgeon, and their sensitive, slightly goofy teenage son (Martí­n Piroyansky).

The two teens click, awkwardly and with some shocking (albeit hormonally natural) developments, but the coolly shot story focuses more on the uneasy overlap of the two fathers. Based on a short story by Sergio Bizzio, XXY is a directing debut for veteran writer Lucí­a Puenzo, daughter of Luis Puenzo, himself the Oscar-winning director of The Official Story. Stylistically, this resembles the hothouse family dramas of Ingmar Bergman and Luchino Visconti, as well as the dreamily morose movies of current compatriot Lucrecia Martel (La Ciénaga and The Holy Girl).

Puenzo avoids predictable plot turns, and an aura of luminous mystery is maintained throughout. But the hand-wringing is unrelieved and she sticks too doggedly to obvious symbols: when you see someone chopping carrots in close-up, the readiest response is to laugh. Also, for someone so concerned with the mutability of sex and sex roles, she is remarkably uninterested in the personalities or conflicts of adult women. Still, the film leaves you pondering the more difficult essentials: mainly, why humans think they have to so thoroughly choose who, how, and with what it is appropriate to love.