Julia, a woman suffering from a degenerative eye disease, becomes engulfed in a mystery after her twin sister, Sara, is found dead in an apparent suicide. Convinced that her sister didn't take her own life, Julia embarks on a quest to uncover the truth. As her vision deteriorates, she reconnects with Isaac, Sara's caretaker, and starts retracing Sara's final days. The investigation leads her through a treacherous path of hidden secrets and invisible threats, with disturbing encounters that suggest Sara may have been stalked by a malicious, unseen presence.

As Julia's condition worsens, she battles both her impending blindness and the escalating tension surrounding Sara's mysterious death. She discovers eerie clues and unsettling pieces of Sara's life that lead her deeper into danger. The line between reality and delusion blurs as Julia faces increasing peril. Gripped by fear and determination, she must find ways to navigate through the darkness, both literal and metaphorical, to uncover the malevolent force responsible for her sister's fate.