If April and her daughter Valeria were guests on “The Jerry Springer Show” — or the trashy talk show’s south-of-the-border equivalent, José Luis — the episode might conceivably be called, “First my mom stole my kid, then she took my baby daddy!” Such outrageous tabloid behavior is almost too extreme to be believed, and yet “April’s Daughter” director Michel Franco displays an almost maddening sense of restraint when reenacting exactly that kind of family dysfunction, repeating (without necessarily advancing) the style of his 2012 success “After Lucia,” which also premiered in Cannes’ Un Certain Regard section.

Although the Mexican director’s odd, arm’s-length approach may be celebrated in a festival context (“April’s Daughter” won this year’s UCR Jury Prize), it’s too cold and disengaged for most moviegoers, which severely limits the audience for a story that, if told in more conventional terms, would have no trouble attracting interest. Likewise, those who connected with the incredible depth of Spanish actress Emma Suárez in Pedro Almodóvar’s “Julieta” (particularly in those scenes when the character worries about the whereabouts of her missing daughter) will have a hard time adjusting to her role as April, who’s more competitive than maternal toward her two kids, dowdy Clara (Joanna Larequi) and skinny 17-year-old Valeria (Ana Valeria Becerril).

The pair look nothing like sisters, and Franco does little to help us puzzle out the fact that they are so related. It’s hardly obvious as Clara prepares a meal in the kitchen (we could be excused for thinking she’s a rich family’s housekeeper) while sounds of enthusiastic sex emanate from behind the door of a nearby bedroom. Out walks Valeria, naked and pregnant — and weirdly shameless to boot. It’s as if the young lady is flaunting her newfound sexuality in front of her homely older sister, which could explain why Clara decides to report the situation to their mother, over Valeria’s explicit objections.

Frankly, it’s anybody guess why characters do what they do in “April’s Daughter,” which may be both realistic and admirably nonjudgmental on Franco’s part, but it makes for a confusing and at times clinical moviegoing experience, as the director applies his detached Michael Haneke-like style to material that begs a certain amount of clarification. When April arrives a few scenes into the movie, she looks young and beautiful enough to be Clara and Valeria’s sister — an incorrect assumption that she openly encourages. April is a fascinating character, playing the role of mother when it suits her, yet fiercely jealous of her two daughters, and too blind to recognize the rivalry or the damage it can do.

Valeria naively thinks she will be able to marry her boyfriend Mateo (Enrique Arrizon) and raise the baby on their own, but April has other ideas. After first insisting that she plans to help the young family get started, she betrays her underage daughter and signs adoption papers taking custody of the infant. That much seems harsh but still understandable, considering the fact that even with her pregnancy bump (a makeup effect so convincing, you’d think Franco found the actress in that condition), the sylph-like Valeria looks hardly more than a wisp of a girl herself. But she’s nowhere near as incompetent as her mother makes her out to be, and she’ll soon surprise everyone with her mama-bear cunning.

As if depriving Valeria of her baby weren’t bad enough, April makes a move on Mateo, appealing to the clueless young father’s shaky sense of responsibility to talk him into moving with her to Mexico City: In effect, if he wants access to his own child, he must agree to leave Valeria and live with April instead. In retrospect, Valeria was right to hide her pregnancy from her mother, though she couldn’t have imagined such a double-cross, and the situation only gets crazier from there, building to a mortifying scene in which the baby is put at unconscionable risk.

No doubt stranger things have happened in both Lifetime movies and real life, and yet, the fact that Franco shows no judgment makes April’s behavior all the more chilling. But even if his technique refuses to comment — with no score and minimal camera movement, the locked-down technique deprives us of the closeups we so badly crave — Franco’s choice of story speaks volumes. What begins as an almost generic commentary on the tragedy of teen pregnancy evolves into a far more singular indictment, in which we come to understand not only that Valeria’s condition results from an absence of parental supervision, but also that she alone can save her baby. In a world where nothing is sadder than an unwanted child, the startling last act offers a ray of hope. When two women fight for custody, it’s a sign that the kid stands a chance.