黑道人物马田改邪归正,却为偿还昔日一笔人情债而毅然再投身黑帮买卖。岂料这次交易逼使马田堕入陷阱,被夹在黑白两道中间。在家人与自己性命备受威胁之下,他只好一面替警员加云作卧底,一面为黑帮头目尊尼亚做买卖。 马田为求早日脱身,遂制造机会,让警方尽快把尊逮捕归案,瓦解黑帮,可是警方以证据不足为由释放了尊,致使马田的处境变得岌岌可危。Small-time crook Nick Bianco gets caught in a jewel heist and despite urgings from well-meaning district attorney D'Angelo, refuses to rat on his partners and goes to jail, assured that his wife and children will be taken care of. Learning that his depressed wife has killed herself, Nick informs on his ex-pals and is paroled. Nick remarries, gets a job and begins leading a happy life when he learns one of the men he informed on, psychopathic killer Tommy Udo, has been released from custody and is out for revenge against Nick and his family.