When a reporter claims that New York police are on the take letting the mob run its horse parlors at will, a shocked District Attorney Michael Norris decide to do something about it. Not knowing who can be trusted on the force, he turns to recent police academy graduates to go undercover and find the corrupt cops. Among them is Pete Harris, a 10 year Marine Corps veteran. His focus is on Lil Polumbo, recently widowed after her husband Gus' truck ran off the road. Rumor has it that Gus was heavily in debt to the mob and killed himself so his wife could collect on his insurance. When the mob learns that Harris is a cop, they try to kill him but it doesn't go as planned and kills someone close to him instead. Pete decides to get the killers at any cost.

故事发生在美国路易斯安那州，在这里，贪污腐败的风气盛行，买官卖官早已经不是什么背地里的稀罕事了。为了整顿规章制度，美国上议院的议员罗根贝利（雷蒙德·沃伯恩 Raymond Walburn 饰）奉命来到了此处，这令市长感到非常的恐慌。于是，市长决定将所有的违规行为都甩锅到一位名叫吉姆（Max 'Slapsie Maxie' Rosenbloom 饰）的男子身上。
一次偶然中，吉姆邂逅了从维也纳流亡至此的美丽女孩玛丽莲（菲莉丝·鲁思 Phyllis Ruth 饰），楚楚可怜的玛丽莲很快就令吉姆坠入了情网之中。这个突如其来的女孩打破了市长筹划缜密的计划，与此同时，吉姆发现，玛丽莲心里所爱的男人竟然是罗根贝利。