故事以谜一般的数字23作为切入点，产生了一种不可抵挡的黑暗力量，这种力量让主角沃尔特·斯派洛幸福的田园生活陷入了痛苦的心理折磨之中，并引导着他走向死亡，而他所爱的人也不能幸免于难。 　　这一切，都开始于一本名叫《数字23》的神秘小说……从沃尔特翻开它的那天起，就再也无法对此释怀，小说中所描写的一切都与他的生活不谋而合，它就像一面镜子，一面让沃尔特胆战心惊的镜子，迫使他面对尘封已久的过去和遥不可及的未来。

16-year-old Mark meets local girl Rachel on the internet, he begins an intense online relationship. He quickly finds that he’s besotted, that he’ll do anything for her, even befriend her awkward, loner brother, John. When Rachel, who is trapped within the grips of a possessive boyfriend, is murdered, Mark and John make plans to avenge her death. Their actions draw the attention of a secret government department as they unwittingly stumble upon an ongoing operation. Soon Mark is recruited to commit a crime that made British legal history.