Rhiannon Lewis (Ella Purnell) is a quiet wallflower working at a dreary local newspaper in the fictional English town of Carnsham.

Overlooked at work, haunted by bullying, and grieving her dying father and beloved dog, she reaches a breaking point in Episode 1. What begins as a moment of catharsis spirals into a calculated killing spree targeting those who've wronged her. As she steps into a junior reporter role and gains confidence, she manipulates the news cycle—especially involving her school bully, Julia (Nicôle Lecky). With each calculated move, she questions: can she maintain her deadly secret while retaining control and power?

In Season 1’s climax, Rhiannon's world unravels as cracks appear in her relationships, leading to a shocking finale.