Lou de Laâgae, left, and Joséphine Japy in Breathe (Toronto International Film Festival)

She’s your best friend. Your cruelest enemy. Sexier than you. Cooler. No one makes you feel as alive as she does. And no one knows better how to make you feel so small. She stole your boyfriend. Turned your girlfriends against you. But you’ll do anything to be around her. You love her. You hate her. Above all, you can’t live without her.

No bond burns like the passion between two teenage girls. Directors know it. Inspired by female bonding’s out-of-control emotions, obsessive attachments, and the sensual awakening of nubile bodies, filmmakers have whipped up a cinematic subgenre ranging from Single White Female to Blue Is the Warmest Color. Now actress/director Mélanie Laurent’s taut, empathetic Breathe arrives in this sometimes iffy category, building tension with a bracing palette of techniques up until the shocking bitter end.

Charlie (Joséphine Japy, who evokes Katie Holmes in a straight-edge, melancholy key) awakens to the sound of her mother’s tears. Maman and Papa are quarreling again, and it’s time for the morning slog through Charlie’s dreary provincial town to the lycée, where Charlie will hang out with her loyal, old-hat friends.

But today someone different comes into the frame: Sarah (Lou de Laâge), a voluptuous troublemaker with the allure of a spiteful young Isabelle Adjani. Sarah comes from an exotic, sophisticated background. She’s more quick-witted and ballsy than the surrounding dorks, and she lets them know it. And when she zeroes in on Charlie, the unhappy only child from an unstable household falls hard. The starting gun is off for consuming love, line crossing, and betrayal.

Breathe pushes a few well-worn buttons. House music and tequila drive one teen party wild. During spring break, Charlie invites Sarah to join her and her mom on a family camping trip, but struggles with jealousy as Sarah wantonly flirts with everyone in sight. The two take part in more than one kiss, a lesbo-light amuse-bouche of the genre, and in a familiar overlapping-identities scenario, Charlie bristles as Sarah usurps her mother’s attentions.

But Breathe stands out from the pack for two main reasons. Emotions run deep and complex. Charlie seems too modest and sensible to fall for Sarah’s bait, but we squirm when she can’t tear herself away, even when Sarah’s manipulations turn Charlie’s once-comfortable school into a bear pit of shame. Japy underplays her character until events force her to crack. As Sarah, De Laâge hints at something sad behind unpredictable charm and cruelty. A secret becomes clear to viewers (and to an eavesdropping Charlie) in a remarkable shot taken from outside a dingy apartment building—where voyeurism gives way to pathos. Like the tormented Charlie, the tormentor has her own dread to face.

Canny stylistic touches elevate the film, too. Shots veer smoothly between airy, backlit naturalism and stagy intensity. Sound cues such as an overheard argument or the rustle of an empty bed set the emotional tone for scenes. Strategically using these tactics, Breathe manages to be hard-hitting and subtle at the same time.

“You make me play the bad guy. It’s unbearable,” hisses Sarah at Charlie right before the movie’s startling end. Breathe leaves an echoing silence, an unbearable void that sucks the wind out of all the drama and passion that has come before.