On Sunday, July 23, 1967, the Detroit Police Department stage a raid on an unlicensed club during a celebration for returning black veterans from the Vietnam War. While suspects are being arrested, a crowd forms and starts throwing rocks at the officers before looting nearby stores and starting fires, beginning the 12th Street Riot. With state authorities, elected representatives and emergency services unable to maintain any semblance of order, Governor George W. Romney authorizes the Michigan Army National Guard and President Lyndon B. Johnson authorizes Army paratroopers to enter Detroit in order to provide assistance. On the second day of rioting, two cops pursue a fleeing looter. One of them, Philip Krauss, kills the man with a shotgun against orders but is allowed to remain on duty until his superiors can decide whether to file murder charges.

The Dramatics, a professional black R&B group, arrive in Detroit hoping to score a recording contract. Seconds before their scheduled performance at a music hall, the police shut down the venue and order them to leave the city. En route, their bus is attacked by rioters and the group splits up, with lead singer Larry Reed and his bodyguard Fred Temple renting a room at the local Algiers Motel for the night. They meet two white girls, Julie Ann Hysell and Karen Malloy, who introduce them to their friends Carl Cooper, Aubrey Pollard, Jr., Michael Clark and Lee Forsythe. Carl Cooper and another friend stage a prank using a starter pistol, upsetting Hysell and Malloy, who move to the room of Karl Greene, a Vietnam War veteran, while Reed and Temple return to their own room.

Melvin Dismukes, a private security guard, is assigned to protect a grocery store from looters and ingratiates himself with the Guardsmen. Cooper decides to fire several blanks from his pistol in the direction of the troops to frighten them but they mistake it for a sniper attack and pinpoint it coming from the Algiers due to the pistol’s muzzle flash. Led by Krauss, the Michigan State Police, National Guard and Detroit Police arrive at the motel to investigate. Entering the building, Krauss kills Cooper when he tries to escape and plants a knife next to his body as he bleeds to death.

The police round up everyone in the hotel and line them against the wall, demanding to know who the sniper was. Despite not finding any weapon during a search of the room, Krauss terrorizes and interrogates the occupants of the hotel. Dismukes arrives to try to help. Unwilling to get involved, most of the state police and National Guard leave without informing anyone of Krauss’s abuse.

Krauss orders several suspects to be moved to different rooms and subjected to mock executions to terrify the others into confessing. One officer, Ronald August, actually kills Pollard, as he did not understand that the executions were supposed to be faked. Hysell and Malloy are taken to an upstairs room, with Hysell’s clothes being accidentally torn off. Disgusted, a Guardsman returns and manages to get them released from custody. Fearing arrest, Krauss permits the remaining three men to leave but only if they swear to keep silent. Greene and Reed agree but Temple is shot twice in the chest by Krauss after he persists in telling them that he sees a body.

As the riots die down, Dismukes, while working his other job in a factory, is arrested and charged with murder after Hysell identifies him as being present at the Algiers that night. His fellow officers are questioned as well and when everyone except Krauss confesses, they are also charged. Reed, whose singing career has stalled due to the trauma he experienced, is summoned as a witness to testify. The judge ultimately refuses to accept any of the confessions as evidence and without a solid case, the all-white jury acquits Dismukes and their co-defendants of all charges. Dismukes confronts the three officers but finds himself powerless to get any justice for the victims.

The film ends by explaining what became of the participants: Dismukes moved to the suburbs to escape death threats and resumed work as a security guard for companies including Sears Roebuck. Although Senak, August and Paille were found not guilty of criminal charges, they never returned to active duty. Paille died on September 9, 2011, while Senak and August were arrested and remain in prison. Years later, a civil court ruled against one of the officers and he was ordered to pay a fine to Pollard’s family of $5,000 ($62,000 to each of the rest of the families). Temple’s family sued the city of Detroit for wrongful death but the city would not admit guilt. Cooper’s starter pistol was mysteriously never found. Hysell left Detroit, raised four children and now works as a hairdresser. The Dramatics broke out in the 1970s with several hits and continue to perform to this day. Reed never rejoined the band; he lives in Detroit and sings in a church choir.