Five years ago, while she and her husband were working late, their daughter was tragically murdered at home. Five years later, to her astonishment, a long-unused phone accidentally rings. Driven by a mysterious impulse, she answers the call, which connects her to the time just before her daughter's death five years ago. The phone becomes a bridge between different timelines. In her desperate attempts to save her daughter, she repeatedly alters the timeline, triggering a butterfly effect. Through her efforts and the clues she pieces together, she uncovers truths she never knew: years of marital betrayal, the identity and motive of her daughter's murderer, and other emotional entanglements. Ultimately, she chooses to sacrifice her own life to save her daughter's. However, five years later, in another timeline, the daughter, now grown, uses the same phone to connect with her mother from the past, initiating another round of mutual redemption between mother and daughter.
