The true story of British Caribbean twin sisters June (Letitia Wright) and Jennifer Gibbons (Tamara Lawrance), who grew up in Wales. By the time they reach the age of eight, they communicate only with each other. As the only Black children at school, they are bullied, and are eventually sent to a special school. Because of their continued silence, they begin to see a child psychologist, but they remain silent, creating a rich, fascinating world to escape the reality of their own lives.
When they reach their teenage years, they buy a typewriter, with a plan to become professional authors. After the girls discover drugs, they begin committing crimes such as robbery and arson, which lands them in a high-security psychiatric hospital.
Based on the best-selling book by Marjorie Wallace.