The story follows two vulnerable teenage girls, who in the summer of 1995 are accused of murdering their schoolteacher. For seventeen years, the two girls are forced to go their separate ways and lead very different lives. But now in 2013, they are forced to confront each other and their dark, shared history.
Serena returns to her hometown for the first time in seventeen years, stirring up memories of the secret she has concealed from her husband and daughter. Serena is haunted by the memory of a teenage love-affair with her teacher, Mr. Halnsley - an affair that ended with his brutal murder. Poppy returns to the same hometown after seventeen years in prison. Poppy was found guilty of murder -‐ a crime she still insists she did not commit. And now she’s out, she knows the only way to get her life back is to find Serena and force her to admit the truth about what happened that night.
Poppy wants revenge and Serena finds it hard to block out the upsetting memories from her past. She turns to her mother for support but after Rachel’s health takes a turn for the worse, she realizes that this is a burden she must face on her own. Serena decides to report Poppy to the probation services, but as she remembers the darker side of Marcus, she remembers the support offered by Poppy. Lifeguard Al is able to persuade Poppy to go out for coffee and she starts to confide in him.
Poppy comes face to face with Serena for the first time in seventeen and discovers that her burgeoning romance with Al is to be shortlived, because he is a journalist. After she is then arrested for approaching Serena, she hits an all time low. Serena’s life also takes an unexpected turn for the worse after her identity as the second Ice Cream girl is revealed to Evan and Vee. Evan leaves taking Vee with him and Serena decides thst it is time to confront the past once and for all as she visits Poppy in prison. Both girls deny murdering Marcus and as they piece together their memories of the fateful night they both finally believe the other is telling the truth. Serena attempts to find out who really did kill Marcus but as she unpicks the past, she uncovers a secret that will turn her world upside down.