Seher, a young and beautiful girl, lives with her father, but her sister Kevser is estranged from the family after marrying into the Kirimli family. Their father cuts ties with Kevser and cannot forgive her. Despite Seher's longing to reunite with her sister, she struggles to convince their father to make amends, leaving her in the dark about Kevser's new life.
Tragedy strikes when Kevser passes away in an accident, leaving behind her son, Yusuf. In her final moments, Kevser entrusts Yusuf to Seher, urging her to protect him from the Kirimli household. Devastated by her sister's death, Seher takes on the mission of becoming Yusuf's guardian and fulfilling Kevser's wishes.
Seher approaches the Kirimli house to meet her nephew but faces challenges. Yaman Kirimli, a strong and distrustful businessman, considers himself the rightful guardian of Yusuf after the passing of his brother. Yaman is known for his strict rules and lack of compassion, adamantly refusing to let Seher take custody of Yusuf. He tracks them down and takes Yusuf back.
Seher, fueled by her innocence and patience, stands up against the formidable Yaman in a battle for custody. Meanwhile, little Yusuf finds himself caught between two warring sides — his aunt Seher and his uncle Yaman. While Seher fights for Yusuf's well-being, Yaman's cold-hearted nature poses a challenge.
The Kirimli house is filled with cunning individuals, and although Yusuf is protected by Yaman, he craves affection and tenderness. Seher's only option is to live in the Kirimli house to safeguard her sister's legacy and provide care for Yusuf.
Seher attempts to pursue a custody case, but she soon realizes that winning against the Kirimli family is a daunting task. Left with no choice, she moves into the Kirimli house to stay close to Yusuf and protect her sister's legacy.
The story of the TV series 'Legacy' (Emanet) revolves around Seher, a young girl, and Yaman, a powerful man, who find themselves entangled in the care of their 5-year-old nephew. Will Seher be able to fulfill her sister's dying wish and care for Yusuf? Can Yaman learn to trust Seher? Will they put aside their differences and collaborate in raising Yusuf? Can Seher protect her sister's legacy? And why does Seher's father disapprove of the Kirimli family?