The story takes place in a small town called "East City", where Mel (Kate Winslet) is a detective who lives and works. Every day, Mel has to deal with all kinds of trivial matters in the town. These things pile up together, which inevitably makes her feel physically and mentally exhausted. One day, a murder broke the quiet atmosphere of the town. A teenage mother named Irene (Cailee Spaeny) was found dead on the river beach. A leaked video shows that on the day of her death, Irene had been bullied by her ex-boyfriend Dylan (Jack Mulhern) and his current girlfriend Brianna (Mackenzie Lansing), and Mel arrested the two without hesitation. The impact of this case quickly swept the entire town like a butterfly effect. For a while, everyone around Mel seemed to be involved in the case.