To raise surgery fees for her seriously ill younger brother, Casey is forced by her stepmother to marry into the top wealthy Lowen family instead of her stepsister, forming a secret contract marriage with the mysterious groom who never shows his face. At the wedding, the groom covers his face the entire time, and the weird atmosphere inside the wealthy family makes Casey feel something is wrong. On their wedding night, she accidentally discovers her husband Seren’s secret — his weak appearance during the day is a disguise, and at night, he crawls out of a transparent shell, going through the alienation process of the heir’s awakening. Casey is forced to keep the secret, and during her time with Seren, she sees through the cruel truth that the Lowen family treats him as an "heir tool" and finds that her genes are the key to Seren’s final transformation. From forbearance and compromise to brave resistance, Casey and Seren join hands to expose the family’s human experiment scandal and destroy the experimental system on the night of the consortium’s listing press conference. In the end, the wealthy empire collapses, and the two break free from the cage, gaining their own freedom and new life.
