Karen McCann is a happily married mother of two with a satisfying job and good friends. Life is rewarding; her world makes sense. Karen has played by the rules, and she lives secure in the assumption that things always turn out for the best. Suddenly, however, her safe, ordered existence is shattered when a stranger enters her home, murders her daughter and, despite overwhelming evidence, is set free on a legal technicality. Outraged, grief-stricken and obsessed with achieving justice, Karen embarks on a dangerous personal journey, and even she doesn't know how far she will go to find peace.