For twenty years, Holly has tried to forget that terrible day. Then the note arrives:I KNOW WHAT YOU DIDBeneath the message is a date she can never escape - 29 April 1999. Desperate, Holly flees to Spain seeking sanctuary with her sister, Emma. But Emma is fighting her own dark battles, and the refuge Holly hoped for quickly unravels. As the sisters' hidden lives slowly surface, Holly is forced to face the truth she has spent decades hiding from. Running from the past was never going to be enough. Someone knows what happened - and they want Holly to pay.