33-year old Han Je In is a mystery novelist who is notorious for habitual false reporting to the police in town. Her only friend is police officer Rok Hwan, who has had a crush on her since childhood. One day, Je In hears a scream of help from an apartment upstairs and reports that a serial killer lives above her but no one believes her. Convinced that Jason, the handsome man living upstairs, is a serial killer, she asks Rok Hwan to help follow him around with her. But as she learns more about Jason in her pursuit to uncover the truth, she begins to fall for him. Seeing her in this state, Rok Hwan feels a tinge of jealousy.
Sam and his team are members of a Serious Crime Unit in the District Crime Squad. The Team successfully arrests a international crime organization's leaders, Night. At the Court, Ann, a prosecutor and Sam's financee, tries her best to convict Night. However, finally, Night is convicted on only one charge and sentenced to three years imprisonment. Night vows to take his revenge and destroy the couple one day. Ann and Sam take a trip to Paris and the assassin monitors them and kills Ann. Three years later, Sam has escaped to Tai O, a fishing village and a look-alike Japanese tourist named You comes and the romance begins again; however, what Sam doesn't know is the assassin was You.
