There are times when life challenges us in ways we never imagined. When our routine is interrupted by something so unexpected and overwhelming, we are forced to confront the fragility of our existence and the complexity of our emotions. Contract of Two Hearts is a story about these moments — about the encounter between two seemingly separate lives, but which, by a mystery of fate, intertwine in a way that no one could have foreseen. Han Seo-jin, a woman with a fragile heart and a life full of dreams and plans, sees her world turned upside down when she is diagnosed with a rare heart condition. The only solution: a heart transplant, something that could save her life, but at the same time, throws her into a sea of uncertainty. On the other side, Han Ji-hoon, a closed man, immersed in his own world of responsibility and distrust, finds himself confronted with the mysterious death of his twin brother, Jae-ho. The pain of loss is compounded by secrets he is not ready to face, but which somehow connect him to the woman who received his brother's heart. A chance encounter filled with lies turns into something deeper and more complex, leading both to question their own truths. In this book, we explore the power of forgiveness, the weight of guilt, and rebirth through pain. It is a story of transformation, of difficult choices, of lives intertwined by fate, and above all, of the search for true love—the one that, even in the face of the greatest challenges, has the power to heal us. Prepare to embark on this emotional journey, where each heartbeat brings a new mystery, and each choice defines the path to redemption.