The recently deceased of a nameless French town mysteriously come back to life, elegantly emerging from their graves in a serene procession out of the cemetery. The town's leadership, spearheaded by the mayor, Victor Garrivier, rallies to create a plan for accommodating these resurrected individuals and facilitating their reintegration into society. He reveals to the town council that this phenomenon has been unfolding for approximately two hours across France, resulting in an astonishing return of around 70 million people nationwide, many of whom are elderly. In their tiny township, over 13,000 of the deceased, all who had passed away within the last decade, are now back.
However, the challenge of reintegration becomes apparent. Those known as "the returned" exhibit symptoms akin to severe concussion—showing signs of disorientation, disrupted sleep, and a tendency to wander aimlessly. Former professionals among them are relegated to simple, menial jobs as it becomes evident that while they can perform basic tasks, they struggle with spontaneous problem-solving and planning, leading to the unsettling notion that their consciousness might be a mere facade. Although they function sluggishly throughout the day, a doctor, Frédéric Pierrot, begins to harbor suspicions about their true state, having observed some of these returned individuals covertly attending spirited nighttime meetings where their symptoms appear to dissipate.
Amidst these developments, emotional reunions take place: the mayor's wife, Catherine Samie, who lost her battle with cancer, finds herself back with her husband; a young boy, Saady Delas, reunites with his parents, Djemel Barek and Marie Matheron; and a young man named Jonathan Zaccaï reconnects with his wife, Géraldine Pailhas. Although initially hesitant to embrace him, Rachel gradually warms to Mathieu, and the two eventually rekindle their romance, culminating in an intimate encounter. Meanwhile, the concerned Doctor Gardet watches with unease as Rachel and Mathieu grow closer, and he tries to alert her to possible risks, only to be dismissed.
In a shocking turn, the town is rocked by a series of explosions, seemingly orchestrated by the returned in an act of sabotage without any injuries. As turmoil ensues, these individuals retreat into a network of underground tunnels, prompting the mayor to attempt to stop his wife from joining the others but succumbing to illness. After a poignant moment where Martha tells him to "give in," the mayor dies, only to later reappear among the returned within the depths of the tunnels. In a drastic response, the military unleashes a gas that places the returned into a permanent coma.
Having assisted some returned individuals in reaching the tunnels, Mathieu makes his way back to Rachel, recounting the story of his fatal car crash, which occurred when he had been searching for her following an argument. As he bravely steps into the darkened corridors of the tunnels, Rachel, grasping the weight of their love, kisses him tearfully before he fades from her sight. She emerges back to the surface only to witness the military carting away the lifeless bodies of the comatose returned, laying them atop their original graves, where they ultimately vanish into nothingness.
