Clarie, a maid suffering from insomnia and distrust after being betrayed by her former fiancé, discovers that the beautiful count who frequents the library is actually a dangerous vampire. She proposes a contract marriage: she wants the status of a countess to pursue her dream of becoming a writer, while he desires her sweet blood. But after the vampire drinks her blood, Clarie realizes she can finally sleep peacefully without nightmares. As they comfort each other night after night, their fake marriage slowly turns into something irreplaceable in this dark, romantic fantasy set in a British-inspired world.