Kerosene Stars: Talk Talk (2016)

There's a serial killer loose, and no one knows who it is-- not even the hard-boiled detective of the town. When a mysterious lady shows up at his office one day with romantic intentions, he becomes suspicious of her. One night, he trails her secretly and discovers that she drinks a potion which transforms her into a bloodthirsty monster. Conflicted, he returns to his office to review the facts. She meets him there, and seduces him into confusion only to ensnare him as her next victim.