The slums of Rio de Janeiro, Brazil, are the "City of God" and a place where even the devil would sigh and turn away. A Pao (Alexandre Rodrigues) takes us here, and he witnesses the chaotic life here that has been wrapped up in brutality, greed, revenge, ambition, betrayal, plunder for more than 20 years, and the catastrophic gang fight that eventually led to it. Although he had to survive among the gangsters since he was a child, his timid character and self-protection instinct have enabled him to live in peace. In the early 1960s, A Mao, A Jia and A Dai were the "three young heroes" here. After robbing the hotel, the three of them parted ways. A Jia returned to the arms of God, while A Dai and A Mao paid the price with their lives. In the 1970s, Douzi (Douglas Silva), a younger brother of the "Young Three", became the "bull" in the slums by virtue of his ruthlessness and continued to annex other people's territories. His business also upgraded from robbery to the more lucrative drug trade. Benny (Phellipe Haagensen) also rose to prominence with him. Benny met the beautiful Andilica (Alice Braga) and was ready to retire. At the farewell party, he was accidentally killed by his rival. In grief, the "bull" gathered people to avenge Benny, and the fight between gangs began. At this time, A Pao became an apprentice photographer at a magazine by chance. His camera captured the hideous children holding guns and bullets, and the endless feud between gangs.