美國政黨新建國元老會(NFFA)為了把國家犯罪率降至1%，決定在一個與世隔絕的社區進行一個極為偏激的社會實驗 — 「殺戮日」— 12小時內，殺人等所有罪行均毋須背負刑責。這個晚上市民可為所欲為，釋放內心的仇恨和戾氣，社會的矛盾卻同時因實驗去到可承受的臨界點。為了殺戮，為了求存，人性受到前所未有的考驗。而過了這晚，一切都不再一樣！

當大家以為國家回復正常秩序，層出不窮的暴亂依然持續，血洗街頭。蒙面殺手們突襲德州一個有錢人家的牧場，牧場主人兒子與工人為保護家人奮力反抗，與狂屠展開生死戰——連場終極冷血廝殺，是否為系列寫下句號？

美國政府誠邀各位一起參與一年一度的國定殺戮日。在「國定殺戮日」的12個小時，任何罪行（包括殺人）均毋須背負刑責，警察和醫院將全面暫停提供所有緊急服務。這一天，有人以暴易暴，為求報仇雪恨；有人肆意犯罪，為滿足一己之慾；有人掙扎求存，只望絕境逢生。這一天，全美再次進入無政府狀態…

Undercover U.S. agent Bill Wilson makes the bust of his career taking down a cartel leader. Hiding the evidence in his home exposes his family to a brutal targeting on the night of the annual Purge, the deadliest night of the year.

As Carl Black gets the opportunity to move his family out of Chicago in hope of a better life, their arrival in Beverly Hills is timed with that city's annual purge, where all crime is legal for twelve hours.

After becoming the victim of vicious cyber bullies, Lisa makes a deal with the devil to exact revenge on her tormentors.

In the 1930’s, the workers of the underground, headed by brigades of writers, are in charge to write in real time "the history of the Moscow Metro". Based on their narratives, partially unpublished, the film recounts the first lines construction of the most beautifiul underground in the world, in the light of this "big literary Utopia", stoped by the purges of 1937-38.