Millie has seven days to save Annie Driscoll from a terrible fate. Millie doesn’t know how or why she has been brought into Annie’s life. But she’s sure of one thing: Annie has already been dead for 68 years. Struggling to come to terms with her uprooted life, Millie is living with her father and his new girlfriend in a building which used to house the most famous women’s prison in the UK. The only remnants of that place is the old prison clock in the hall – a clock that has long been silent. When the clock begins to strike again one night, Millie meets a young, terrified woman in a cell. Annie cannot see her, but Millie realises that she may be the key to changing Annie’s fate – a fate that was sealed in 1955. But is there enough time for justice to be done?