银行小职员斯坦利（金•凯瑞 Jim Carrey 饰）老实本分，过着和所有老实人一样的平凡生活。一次，斯坦利在接待金发美女蒂娜（卡梅隆•迪亚茨 Cameron Diaz 饰）时深深恋上了对方，不料蒂娜却是黑帮头目多利安（彼得•格林纳 Peter Greene 饰）抢劫银行前派来打探地形的。多利安随后成功抢劫了斯坦利所在的银行。 一晚，斯坦利意外获得了一个奇怪的面具。戴上面具后的斯坦利变得力大无比、身手敏捷。斯坦利开始四出捉弄平日欺负他的人，并抢走了多利安劫得的巨款，与蒂娜在夜总会尽情飞舞。多利安知道了面具的威力后，用计夺走了面具，斯坦利则被关进了监狱。斯坦利最后能否凭自己的智慧夺回面具，与蒂娜有情人终成眷属? Stanley Ipkiss (Jim Carrey) is a bank clerk that is an incredibly nice man. Unfortunately, he is too nice for his own good and is a pushover when it comes to confrontations. After one of the worst days of his life, he finds a mask that depicts Loki, the Norse night god of mischief. Now, when he puts it on, he becomes his inner, self: a cartoon romantic wild man. However, a small time crime boss, Dorian Tyrel (Peter Greene), comes across this character dubbed "The Mask" by the media. After Ipkiss's alter ego indirectly kills his friend in crime, Tyrel now wants this green-faced goon destroyed.