In the depths of Blackwood Group, a timid office girl Evelyn is pushed to the brink. One night, a succubus named Lilith claims her as her perfect vessel and binds her to a contract—feed the demon with her desire every night, and break its seal. Dragged nightly into a dream world, Evelyn is claimed by both the cold CEO Damian and the ruthless director Sera, who share her body and blur the line between dream and reality. As the marks of the contract creep onto her skin and a black button bearing a "B"—and a secret contract left by her mother—surface, Evelyn discovers the truth: this hunt is not a game, but a bargain spanning two generations. Awakening to memories that were never hers, she must choose to break free, or to be devoured.