在这部月光光心慌慌4惊悚/恐怖片中,10年前，残暴无情的迈克尔•梅尔（George P. Wilbur 饰）陷入永久的昏迷之中，周遭的人们得到短暂的宁静。时间推移到1988年10月31日的万圣节，迈克尔被雷蒙德精神病中心的医护人员转去另一个医院。救护车上，医护人员随意的闲谈却唤醒了这个沉睡已有10个年头的恶魔。苏醒的迈克尔得知他姐姐的女儿杰米（Danielle Harris 饰）住在哈登菲尔德，遂将医护人员杀害，只身前往甥女的住处。
被克鲁赛斯一家收养的杰米，多年来持续为关于舅舅的恐怖噩梦所困扰。她想不到的是，那梦中的恶魔即将出现在她的面前，摧毁杰米至今仍未平静的生活……
It's October 30, 1988 and Michael Myers has been in a coma since his pursuit of Laurie Strode, 10 years ago, was finally stopped (events of H1 and H2). However when he is transfered from Richmond Mental Institute to Smith's Grove he awakes when he hears that he has a niece in Haddonfield and after killing the transfer crew he escapes. In Haddonfield, the niece, Jamie, has been adopted by the Carruthers family but keeps having nightmares about Michael (but she doesn't know who he is). On Halloween night, Jamie goes out trick and treating, little knowing that her murdering Uncle is following her and her step-sister Rachel. Rushing to her aid is Dr. Loomis and with the help of Sheriff Meeker starts to search the town for Michael and to find Jamie to protect her. But can anything stop Michael this time?
平庸的继续。迈克尔==超人。
