艾可(Echo)的姐姐佐伊(Zoë)在一年前离奇死亡,从小依附于姐姐的艾可迟迟没能走出伤痛。面对重度抗抑郁的母亲和疯狂忙于工作的父亲,步入的高中的艾可迫使自己坚强独立 。虽然凶手早已落网,但艾可始终认为姐姐的前男友马克(Mark)与她的意外死亡有关。一次偶然,艾可在马克的新车里发现了姐姐生前的日记本,层层谜团看似被逐渐揭开.....而姐姐真正的死因是否与马克有关? 隐瞒在高中生之间的谎言,女孩日记本里不为人知的秘密,当一切水落石出,这起谋杀案件真相的背后又是否还藏有惊天黑暗的阴谋?It's been a year since her older sister's murder, and Echo is still far from being completely all right. Echo has been trying her hardest to be the strong one, while her mother takes too many antidepressants and her father works too much. Now, at the start of her freshman year of high school, Echo receives an unlikely gift from Zoe's old boyfriend: her diary. Echo is hesitant to read it but can't put it down after she gets caught up in Zoe's secret life.