Cara Lockhart has just commenced a life sentence in HMP New Fern, the newest maximum security woman's prison in the country. She was convicted of a murder she is adamant she didn't commit. One morning she wakes up to find her cellmate murdered - shot in the head with a gun that is missing. The door was locked all night, which makes Cara the only suspect. Being the only one who knows the truth, Cara sets about trying to clear her name, unravelling an impossible case, with an investigation governed by a prison timetable. Cara starts to learn more about her fellow prisoners, finding connections between them and herself that she would never have imagined.
