My little boy's room was empty, his bed neatly made. Alarm bells should have rung immediately. Then the knock on the door came. All I remember is a thick fog wrapping itself tightly around me. This couldn't be happening to us.

Three years ago, nurse Zoe's son Ethan was found drowned in a muddy river by their home, along with his best friend, Josh. With no witnesses, their deaths were ruled a tragic accident. 

Heartbroken, Zoe and her family move away from her home. They're just beginning to get back to some kind of normality when, out of the blue, Zoe receives an anonymous email: "You need to find out the truth about what happened to your son. Don't let this rest. Don't believe the lie."

Shaken, Zoe starts an obsessive hunt for the truth. But why is her husband so reluctant to help? And why is Josh's mother so determined not to believe her?