Valérie, Karine Vanasse, and Stéphanie, Evelyne Brochu, are engineering students at Polytechnique Montreal who find themselves caught in a sudden, devastating attack. A troubled young man, Maxim Gaudette, arrives with a Ruger Mini-14, leaves a message for his mother, and enters a classroom in the middle of a lecture. He orders the men to leave and the women to stay, then fires a shot into the ceiling to prove he is serious. He declares his hatred of feminists, and although the women deny being feminists, he shoots at them, killing some and wounding others. He moves through the building—along the halls and into the cafeteria—before continuing to target women in his path.
Jean-François, a male student who had been ordered to evacuate, defies the order and returns in a bid to intervene or assist the victims, hoping to slow the onslaught or save lives. The survivors, Valérie and Stéphanie, work to stay hidden as the threat lingers, with Valérie clinging to a fragile calm and Stéphanie hoping to outlast the danger. Stéphanie is gravely injured in the chaos, and the damage of the day becomes tragically personal for everyone involved.
The killer presses on to another classroom, where he kills a female lecturer before ending his own life, his final act leaving a smear of blood among the victims. The school awaits the aftermath in silence, and the community begins to reckon with what happened, and with the choices made in those crucial moments.
In the days and weeks that follow, the memory of the day continues to haunt those who survived. Jean-François, overwhelmed by guilt for leaving the room and for not doing more to intervene, dies by carbon monoxide poisoning, a private tragedy that underscores the film’s quiet, unflinching examination of responsibility and grief. Valérie, meanwhile, carries the weight of survival into a new phase of life—wearing the Iron Ring as a reminder of her profession and her identity—then learns she is pregnant. She contemplates her future and what she might tell her child, resolving to affirm that the world belongs to her, no matter the challenges ahead, a testament to resilience in the wake of catastrophe.
