Chaebol heiress Sylvia struggles with a rare cyclical fever that requires biological stabilization from beast-kin partners. For years she indulges her vain fox-shifter partner Felix, only to find him ditching her medical crisis to pamper her conniving cousin. Recognizing Felix's narcissistic manipulation, Sylvia breaks the contract on the spot and buys the deed of Seth, an intimidating snake-kin warrior enslaved in the fighting pits.
Seth responds to Sylvia's gentleness with unyielding loyalty, stabilizing her health through his soothing venomous energy. Realizing his golden ticket has vanished, Felix stages a desperate kidnapping, believing Sylvia will crawl back to his embrace. But Sylvia and Seth turn the tables, exposing Felix's crimes and establishing an unbreakable union beyond elite society's control.
