Reeling from a brutal attack that leaves her best friend dead and her badly injured, Lisa Fulbrook flees to the countryside to recuperate. With only vague memories of the event, she isolates herself from her friends and family, spending her days wandering the hills with her dog, Riley. She is plagued by vivid flashbacks and tormented by questions: how did their assailant know them? Why were they attacked? And what really happened that night? As she desperately tries to piece together her memories, Lisa realises that there's another truth still hidden to her, one she can't escape from. A truth that may have been right in front of her all along...