Detective Jameson, once a timid and kind man, transforms into the ruthless "Darkest Officer" after drinking water given by a mysterious woman. He becomes a vampire who feeds on human blood and anxiety, and marries Emilia, a woman auctioned off to him. Despite treating her poorly, Emilia discovers his secret and begins to fall in love with him. Jameson, however, doesn't reciprocate her feelings, instead demanding she sleep with his friend's stepdad to prove her love. As Jameson's powers grow, Emilia becomes his anchor, calming his ruthlessness, but he struggles to acknowledge his feelings for her. Will Jameson fight his hunger or will he succumb to it?