Sirens are mysterious beings whose songs possess the power to charm, control, heal, and captivate anyone who hears them. Years ago, a siren named Sophia was kidnapped by Count Cortez and treated as his personal possession. Soon after, her daughter Aria was born into the same cruel fate. Forced to live as a siren, Aria grows up surrounded by greed, obsession, and horrifying abuse as countless people become consumed by the desire to hear her sing. Among them is the emperor himself, whose madness leads him to imprison Aria deep within the imperial palace, locking her inside a gilded cage after cruelly crippling her to ensure she could never escape.

Having lost all hope, Aria prepares to accept death—until the feared Devil Archduke, Lloyd Cardenis Valentine, suddenly appears before her. Offering both salvation and destruction, he promises to answer her call no matter where she is. In desperation, Aria calls upon him, unleashing death upon everyone around her before finally taking her last breath herself.

But instead of dying forever, Aria awakens once more as her ten-year-old self, given a second chance to rewrite her tragic future. Determined to save both herself and the archduke who once rescued her, she approaches Lloyd with an unusual proposal: a contract marriage that will end in divorce ten years later. However, while Aria intends it to be only a temporary arrangement, the archduke seems to have very different intentions for their future together.