十三，一个听起来就有些阴冷的数字。在一座大厦的第十三层，科学家道格拉斯•霍尔（克雷戈•比克饰）和汉农•富勒（阿明•缪勒－斯塔尔饰）用电脑模拟出一个逼真的1937年的洛杉矶，他们可以通过电脑进入这个虚拟世界，真实地体验1937年的生活与自己。然而一个夜里，富勒被人杀死，种种线索都表明似乎是霍尔所为。可霍尔却对当天夜里的事情全无记忆。这时一个自称是富勒女儿的女人又神秘出现，可霍尔从未听富勒说过自己有女儿……为了找到凶手明晓真相，霍尔循着富勒留下的线索来到虚拟世界中，他离真相越来越近了……近到窒息……Computer scientist Hannon Fuller has discovered something extremely important. He's about to tell the discovery to his colleague, Douglas Hall, but knowing someone is after him, the old man leaves a letter in the computer generated parallel world his company has created (which looks like the 30's with seemingly real people with real emotions). Fuller is murdered in our real world the same night, and his colleague is suspected. Douglas discovers a bloody shirt in his bathroom and he cannot recall what he was doing the night Fuller was murdered. He logs into the system in order to find the letter, but has to confront the unexpected. The truth is harsher than he could ever imagine...