家庭主妇唐娜（Dee Wallace 饰）和另一个男人斯蒂夫（Christopher Stone 饰）有染，当她决定中止这段关系的时候，斯蒂夫却报复性地将他们的关系透露给唐娜的丈夫维克（Daniel Hugh Kelly 饰），夫妻关系顿时陷入僵局。某天，维克以公务之名离开，唐娜则带着5岁的儿子泰德（Danny Pintauro 饰）来到某汽车旅馆居住。 　　汽车旅馆老板的儿子布莱特（Billy Jayne 饰）有一条名叫古卓的圣伯纳犬，古卓偶然被蝙蝠咬了一口，竟由此变成嗜血如命的凶残恶犬，它开始向唐娜母子发起了攻击…… 　　本片根据史蒂芬•金的同名小说改编，并荣获1987年葡萄牙奇幻国际电影节观众评委会奖。Donna Trenton is a frustrated suburban housewife whose life is a turmoil after her husband learns about her having an affair. Brett Camber is a young boy whose only companion is a Saint-Bernard named "Cujo", who in turn is bitten by a rabid bat. Whilst Vic, Donna's husband is away on business, and thinking over his marital troubles, Donna and her 5-year-old son Tad take her Pinto to Brett Cambers' dad's car shop... the car fails, and "Cujo" is very, very sick...