Watchmen

The story takes place in an alternate timeline in which masked, costumed vigilantes fight crime in America, originally in response to a rise in masked and costumed gangs and criminals. In the 1930s and '40s, the vigilantes formed a group called the Minutemen to "finish what the law couldn't." Of the eight Minutemen, three died violently, one disappeared, and one was committed to an asylum. Decades later, a second generation of "superheroes" attempts to form a similar team called the Watchmen. Various historical events are shown to have been altered by the existence of superheroes, such as the assassination of John F. Kennedy and the Vietnam War. The American victory in Vietnam, due to the intervention of the godlike being Doctor Manhattan, leads to Richard Nixon's third term as President following the repeal of term limits in the United States. By the 1980s, however, the Watchmen have been outlawed by Congress after an outpouring of anti-vigilante sentiment in the country, and tensions between the United States and the Soviet Union have escalated the Cold War with threats of nuclear attack.

By 1985, only three Watchmen remain active: the Comedian and Doctor Manhattan, both of whom act with government sanction, and the masked vigilante Rorschach, who refuses to retire and remains active illegally. Investigating the murder of government agent Edward Blake, Rorschach discovers that Blake was the Comedian, and concludes that someone may be trying to eliminate the Watchmen. He attempts to warn his retired comrades—his former partner Daniel Dreiberg (Nite Owl), the emotionally detached Dr. Jonathan Osterman (Doctor Manhattan), and Dr. Manhattan's lover Laurie Jupiter (the Silk Spectre). Dreiberg is skeptical, but nonetheless relates the hypothesis to billionaire Adrian Veidt (Ozymandias), who dismisses it.

After Blake's funeral, Dr. Manhattan is accused of causing the cancers afflicting his former girlfriend and others who spent time with him after the scientific accident that gave him superpowers. Dr. Manhattan exiles himself to Mars, giving the Soviet Union the confidence to invade Afghanistan in his absence. Later, Rorschach's conspiracy theory appears to be justified when Veidt, who had long since made his identity as Ozymandias public before retiring, narrowly avoids an assassination attempt, and Rorschach finds himself framed for murder.

Meanwhile Jupiter, after breaking up with Manhattan, goes to stay with Dreiberg, and the two former superheroes come out of retirement as they grow closer. After they break Rorschach out of prison, Silk Spectre is confronted by Dr. Manhattan. He takes her to Mars and, after she asks him to save the world, explains he is no longer interested in humanity. As he probes her memories, it is discovered that the Comedian was her father. His interest in humanity renewed by this improbable sequence of events, Manhattan returns to Earth with the Silk Spectre.

Investigating the conspiracy, Rorschach and Nite Owl discover that Veidt is behind everything. Rorschach records his suspicions in his journal, which he drops off at a newspaper office. Rorschach and Nite Owl confront Veidt, dressed once more in his Ozymandias costume, at his Antarctic retreat. Ozymandias confirms he is the mastermind behind the Comedian's murder, Manhattan's exile, and the framing of Rorschach; he also staged his own assassination attempt to place himself above suspicion. He explains that his plan is to unify the United States and the Soviet Union and to prevent nuclear war by destroying the world's main cities with exploding energy reactors he helped Doctor Manhattan create under the pretense of providing free energy for the world. Rorschach and Nite Owl attempt to stop him, but Ozymandias easily beats them. Ozymandias then reveals that his plan has already been set into motion: the reactors have been detonated, and the energy signatures are recognized as Manhattan's.

The Silk Spectre and Doctor Manhattan arrive at the ruins of New York City and determine that it must be Veidt's work. They teleport to the Antarctic retreat to confront him, but Ozymandias turns on a news report in which President Nixon states that the US and Soviets have allied against their "common enemy," Manhattan. The heroes are completely helpless to stop it and realize that revealing the conspiracy would only disrupt this peace. Only Rorschach is unwilling to remain silent and, at his own urging, is vaporized by a reluctant Manhattan. Manhattan shares a final kiss with Jupiter and departs for another galaxy.

With the end of the Cold War and the uniting of humanity, Jupiter and Dreiberg return to New York City as it's being rebuilt to begin a new life together. The film closes with a newspaper editor in New York complaining of having nothing worthwhile to print because of the worldwide peace. He tells a young employee that he may print whatever he likes from a collection of crank mailings, among which lies Rorschach's journal.