It's 1985, and Richard Nixon is serving his fifth term as President of the U.S., but is facing an increasingly dangerous nuclear showdown with the Soviet Union. The world is this way due to an original band of superheroes who changed history many decades ago, to be followed by a new group, known as the Watchmen, who took their place.
Yet, after demigod Doctor Manhattan (BILLY CRUDUP), a.k.a. Dr. Jon Osterman, changed the course of the Vietnam War alongside the far more human, flawed and homicidal The Comedian (JEFFREY DEAN MORGAN) -- Edward Blake in private -- Nixon outlawed superheroes, but privately kept those two on the government payroll.
Their former cohorts, however, have gone their own ways. While Laurie Juspeczyk, a.k.a. Silk Spectre II (MALIN AKERMAN), is romantically attached to Dr. Manhattan -- despite his genetically altered blue glow -- and is following in the footsteps of her mother, Sally Jupiter, the first Silk Spectre (CARLA CUGINO), Daniel Dreiberg, a.k.a. Nite Owl II (PATRICK WILSON), wonders whatever happened to their type, and secretly longs for Laurie.
Adrian Veidt, a.k.a. Ozymandias (MATTEW GOODE), the smartest man in the world, has become an ultra-successful businessman, but Walter Kovacs, a.k.a. Rorschach (JACKIE EARLE HALEY) -- so named for his ever-changing inkblot mask he wears -- is still carrying on the good fight, albeit as a shadowy vigilante. When The Comedian is murdered, it's Rorschach who's convinced that someone's gunning to bring down the rest of them, and starts investigating who that might be.
As that occurs and various members of The Watchmen are reunited, Dr. Manhattan and Adrian strive to create unlimited resources for all of humankind, in hopes of circumventing what looks like an inevitable nuclear war that Nixon seems prepared to wage against the Soviets.