At four years old, Leah Martens was the only witness to the murder of two women in a London park.

Now, twelve years later, as the man imprisoned for the murders walks free, Leah desperately tries to remember exactly what she saw that day.

But she's not the only person whose life was scarred forever in that park and whose past now threatens to decide the future.

Two boys are also sucked into the treacherous investigation around the murders.

Fourteen-year-old Charlie, who is plotting revenge with a ruthless man, and the enigmatic Linden, who befriends Leah all the while concealing his shameful past and leading her further into danger.