Alex (the absolutely crushing Inés Efron) is an intersex teenager living—as a girl in the throes of sexual curiosity—on the beautiful, bleak coast of Uruguay. When family friends come to visit from Argentina—including gawky 16-year-old Alvaro (Martín Piroyansky)—the family, the town, and the visitors struggle (some cruelly, some sweetly) with Alex's anomalous anatomy.
The film is a bit overwrought in the metaphor department: Aggressive carrot-chopping, for example, is juxtaposed with a debate about surgery to make Alex, ahem, permanently female. And in an opening scene, Alex's father, who rescues wounded sea turtles (an endangered species, get it?), pries open a dead turtle's shell to identify its sex ("It's a female").
But Alex's fierce, battered confidence in the rightness of her own body; her father's heartbreaking pronoun confusion; and XXY's gentle refusal to judge anyone's choices (or, more importantly, to force choice on anyone) make it a powerful—and refreshingly sensitive—lesson on modern gender.