The story follows the life of Mrs. Dai, a 70-year-old grandmother who feels a profound sense of failure regarding the path her life has taken. Living with her only son, Quang, his wife Vy, and her two grandchildren, Nhon and Tung, she often feels the weight of her struggles. Despite her hardships, she finds solace in her close friendship with Mr. Be, who frequently looks after her.
Feeling the approach of her final years, Mrs. Dai decides to visit a photography studio to take a funeral portrait, wishing to capture her image before she becomes "too old and ugly." However, while preparing for the photoshoot, an unexpected and supernatural miracle occurs, transforming her back into the 20-year-old version of herself. Initially unaware of the drastic change, she only realizes she has regained her youth once she is riding the bus.
Because of her new appearance, returning home is impossible as her own family would not recognize her. She adopts the new identity of Thanh Nga and arranges to rent a room in the house of Mr. Be. Determined to live a life without regrets and seize this second chance, Thanh Nga decides to pursue her long-lost dream of becoming a professional singer. While spending time at a club for elders, she performs a song titled "Diem Xua," and her extraordinary voice immediately captivates everyone present, including Tung, Mr. Be, and a talent scout named Manh Duc. Manh Duc and his assistant, Min Ji, had been searching tirelessly for a unique voice for a TV channel, and they finally find what they were looking for.
Tung is so impressed that he invites her to become the lead vocalist for his music band. She accepts the offer and brings a fresh, new style to the group's sound. Soon, the band is selected by Manh Duc to participate in a major talent show. However, tension arises when Mr. Be discovers Mrs. Dai's personal belongings in Thanh Nga's room. Mistakenly believing that Thanh Nga has murdered the elderly Mrs. Dai, Mr. Be attempts to tie her up to interrogate her. In a twist of events, Thanh Nga manages to tie him up instead and reveals the shocking truth: she is actually Mrs. Dai, just in a younger body. Stunned by the revelation, Mr. Be agrees to keep her secret.
As the band's popularity grows, they secure an opportunity to perform in a live show. Thanh Nga performs "Con tuoi nao cho em," a song that deeply touches the audience and solidifies her rising stardom. During a group outing to a pool with Manh Duc and Min Ji, Thanh Nga demonstrates her inner maturity by preaching to a teenager about the importance of showing respect toward the elderly.
However, the miracle comes with a price. Mr. Be notices that Thanh Nga begins to age whenever she bleeds. Adding to her struggles, Mr. Be's daughter, Duyen, becomes convinced that her father and Thanh Nga are having an illicit affair and angrily demands that she leave the house. This forces Thanh Nga to stay temporarily at the home of Manh Duc. This arrangement creates a complicated dynamic, as Tung becomes jealous of the relationship, completely unaware that the woman he is envious of is actually his own grandmother. Meanwhile, Manh Duc begins to develop genuine romantic feelings for her.
Tragedy strikes just before another major performance. Tung returns home to retrieve his late grandfather's hat, but on his way to the show, he is struck by a truck and rushed to the hospital. Determined to honor him, Thanh Nga performs "Minh Yeu Tu Bao Gio," a piece composed by Tung himself. The performance is a resounding success. In a selfless act of love, Thanh Nga agrees to donate her blood to save Tung. Because of the blood loss, the magic fades, and the youthful Thanh Nga transforms back into the 70-year-old Mrs. Dai.
In the aftermath, Nhon takes over as the vocalist for Tung's band, stepping in as a replacement for the missing Thanh Nga. The story concludes with Mrs. Dai's entire family attending a live show to support Nhon and Tung. As Mrs. Dai exits the theater, she looks toward Manh Duc with a happy, peaceful smile, finally at peace with her life and the memories of her brief return to youth.
