Brother's Blood takes place on the mean streets of a city in decay, where a recently released convict begins to take murderous revenge against his childhood friends, whom he believes let him take the fall for a crime they collectively committed. As the bodies start piling up, one of the friends, now a cop, will stop at nothing to put an end to the murderous rampage and to right the many wrongs of their tragically violent past.
一對熱血虔誠的愛爾蘭裔兄弟,因自衛殺人而得罪黑幫,警署以正當防衛之名無罪釋放。從此之後,二人決定以己之力對抗社會渣滓,購買武器以暴制暴,在朋友洛克(大衛·德拉·洛克David Della Rocco 飾)的幫助下清除犯罪分子。聯邦警探保羅·斯邁克(威廉·達福 Willem Dafoe 飾)負責偵破案件,本來毫無頭緒;但 在黑幫頭子“老爸喬”(卡洛·羅塔 Carlo Rota 飾)僱傭了傳奇槍手“公爵”(比利·康諾利 Billy Connolly 飾)對抗麥克馬納斯兄弟之後,情況卻發生了意想不到的變化……