In an alternate 1985 where superheroes exist but are now outlawed due to their controversial actions, the world stands on the brink of nuclear war between the United States and the Soviet Union. Against this backdrop, the film opens with the murder of the Comedian, a government-sanctioned vigilante. His death prompts another masked vigilante, Rorschach, to investigate a potential plot to eliminate former heroes. Rorschach reconnects with his former crime-fighting partners – Dan Dreiberg (formerly the second Nite Owl), Dr. Manhattan (a superhuman with god-like powers), Silk Spectre II, and the super-intelligent Ozymandias – to warn them of the threat he perceives against their lives. As they delve deeper, they uncover a tangled web of deceit and moral ambiguity.

While Rorschach continues his grim inquiry, Dr. Manhattan faces a personal crisis that leads to him isolating himself from humanity, jeopardizing the balance of global power. Nite Owl and Silk Spectre II rekindle their superhero personas and an old romance, responding to the rising uncertainty and lawlessness. Together, the former vigilantes must confront not only the potential conspiracy but also their own pasts, personal failures, and the complex nature of their legacy. As tensions rise globally and locally, the heroes' actions set the stage for a confrontation that will determine the fate of the world and the very idea of heroism in a morally gray universe.