一群大学生在四月一日愚人节结伴到一无人荒岛的巨宅中度周末，结果碰上血腥的愚人节恶作剧。他们在互相玩笑之余却逐一被杀，而邀请他们前来的富家女莫菲圣琼却始终未露面，这到底是什么回事？影片明显地采用了艾嘉莎克莉丝蒂的侦探名著《十个小印第安人》的故事模式，让剧中人一个一个被杀

　　Life in the Catholic Church of the Holy Redeemer in Detroit is upset by a series of killings whose victims are all priests and nuns. All victims are found with a black rosary in their hands. Father Koesler begins collaborating with the police but soon finds himself in a spot when the killer decides to choose him as confessor.