What would you do if you were suddenly reminded of something you witnessed as a young child, but had only just realised the terrible significance of what you saw?

When Cerys Morgan, a beautiful young student, vanished from a crowded beach in Cornwall while camping with friends during the heatwave summer of 1976 it triggered the largest police operation of its kind at the time. Hundreds of locals joined the search and it made the headlines for weeks, but no trace of her was ever found.

Thirty-four years later Emily Harrison is suddenly reminded of something she witnessed as a young child, and only then realises the terrible significance of what she saw. Horrified she tells the police everything she can remember. The trouble is, even her own parents didn't believe her at the time, so who will believe her now?

Haunted by her memories Emily becomes obsessed and, as the heartbreaking story of Cerys unfolds, she soon realises only she knows the answer. Even when she receives sinister threats - and her contented life rapidly disintegrates around her - she will stop at nothing to find the truth and get closure for Cerys' elderly parents.

What really did happen on her sixth birthday?