在这部惊梦49天惊悚/犯罪片中,高富帅美籍华人李家豪Daniel Lee(刘国雄饰)，在一场与红衣女子交缠的恶梦后，手臂上出现莫名的数字烙痕，数字从49开始一天天减少，梦魇像是倒数般的灼热，身边的人接二连三的离奇死亡，他成为了重大嫌疑犯，科学查证无法解释所有的疑点，却在民俗“观落阴”中找到答案？
29岁、不爱打扮的刘奕臻(任容萱 饰)为何立志成为刑警？陷于痛苦回忆中的她如何帮助自己走出泥潦？她如何协助李家豪一步一步地找出事实的最后真相？
一场伤痕累累的解谜，抽丝剥茧地一一解开，究竟谁能全身而退？谁才是背后的真正主谋？
The same nightmare troubles Daniel every night: A vision of a young lady in red dress continuously appears. A timer counting-back from 49 mysteriously appears on his arm. People around him accidentally died one by one in brutal ways.
