美国阿拉斯加德诺曼小镇，在过去的几十年里当地不断发生离奇事件。许多人神秘失踪，还有很多人被严重的失眠所困扰，自杀案件居高不下。单身母亲阿比盖尔•泰勒（米拉·乔沃维奇 Milla Jovovich 饰）当年曾经历一场诡异的灾难，在那场灾难中，睡在身边的丈夫神秘死亡。在此之后，阿比盖尔开始研究催眠。当得知诺曼镇发生的事情时，她直觉这与自己的经历有很大关系。经过对几名当事人的催眠，阿比盖尔得知他们都有着遭遇莫名生物的经历，在此期间，她更目睹了当事人杀害全家并自杀的悲惨场面。随着调查的深入，真相渐渐浮出水面，然而最为恐怖的事情也随之发生…… 　　本片据传由真实事件改编。In 1972, a scale of measurement was established for alien encounters. When a UFO is sighted, it is called an encounter of the first kind. When evidence is collected, it is known as an encounter of the second kind. When contact is made with extraterrestrials, it is the third kind. The next level, abduction, is the fourth kind. Modern-day, Alaska, where-mysteriously since the 1960s-a disproportionate number of the population has been reported missing every year. Despite multiple FBI investigations of the region, the truth has never been discovered. Here in this remote region, psychologist Dr. Abigail Tyler began videotaping sessions with traumatized patients and unwittingly discovered some of the most disturbing evidence of alien abduction ever documented. The Fourth Kind exposes the terrified revelations of multiple witnesses. Their accounts of being visited by alien figures all share disturbingly identical details, the validity of which is investigated throughout the film.