The Dark

Adèlle travels to Wales to visit her husband James and repair her fractured relationship with their daughter Sarah. The family dynamics are strained as they try to reconnect, setting the emotional stage for the unfolding mystery.

On a windswept cliff, they discover a memorial with a missing plate and the name Annwyn etched into it. Local Dafydd explains that Annwyn is a traditional Welsh concept of an afterlife, foreshadowing the supernatural events to come.

Sarah vanishes on the beach and a strikingly similar girl, Ebrill, emerges in her place. Ebrill is revealed to be the long-dead daughter of a shepherd who once served as the town's pastor.

Ebrill's backstory is revealed through flashbacks: a shepherd father sacrificed others into the ocean hoping to return her from Annwyn. The evil within her returns, and her father and followers attempt to extract or control it with brutal rituals, while Dafydd witnesses and ultimately frees Ebrill.

Dafydd, who refused to throw himself off the cliff, remembers the others' sacrifices. After witnessing the shepherd harming Ebrill, he frees her and unintentionally contributes to the spread of the evil.

Back in the present, Adèlle deduces that Ebrill has returned because Sarah is a living substitute, linking the two girls across time. She realizes that stopping Ebrill requires confronting the supernatural threat rather than mere reconciliation.

In a desperate move, Adèlle throws herself and Ebrill off the cliff into Annwyn, despite James' protests. The leap plunges them into a sepia-toned, misty version of reality where the rules of life and death are blurred.

Inside Annwyn, the film reveals that Sarah had previously attempted suicide following a fight with Adèlle, explaining why the mother desperately seeks a second chance. Ebrill warns that the dead do not get second chances.

During the ritual, Ebrill and her father perform trepanation on Adèlle to draw out the evil inside her, a brutal procedure that heightens the danger she faces. The act dramatizes how the town’s legends have breached the living world, and it raises the stakes of the rescue.

Adèlle breaks free of her bonds, hurriedly searches for a way out, and finally finds a key to a door. She apologizes to Sarah for her selfishness, reinforcing her resolve to save her daughter.

Opening the door, Adèlle rescues Sarah from Annwyn, but her own sacrifice seals the act; she dies before realizing Sarah has been returned to the world. The moment leaves Sarah tainted by the same darkness that haunted Ebrill.

Back in the real world, Sarah bears the evil's stain, suggesting the cycle may continue. James and the others must face the consequences of Adèlle's death and the uncertain future for Sarah.