Fear God, and give glory to him... for the hour of his judgement is come...
Kingdom Come is a reaction to the influence works such as The Dark Knight Returns had on the comic genre. Just as Dark Knight was a reaction to its present, starting a phase of edgier and darker toned comics, where superheroes became morally flawed and somewhat ruthless vigilantes taking pleasure from the violence of crime fighting rather than seeking true justice. So too does Kingdom Come, react, and also mirror Frank Miller's great work, being in essence, "The Man of Steel Returns".
In one of the many futures of the DC Universe, the heroic golden generation of superheroes have retired (or taken to simpler responsibilities). Leaving the day to day protection of Earth to the younger meta humans, whose new methods of justice are accepted by the people, despite a warning from Superman that their would be consequences. When his fears are realised, he is pleaded to return by Wonder Woman and put things right.
Kingdom Come is truly epic, including at least a mention of many iconic DC characters. The writing borrows much from classical and biblical themes and iconography with literal parallels to the war for heaven and book of revelation. The Minister and Spectre play the roles of Dante and Virgil respectively, who guide us through the narrative as it unfolds.
The highly detailed watercolour artwork itself adds to the classical approach, giving a heightened visual style which emphasises the grandiose nature of the story.
If your looking for a good, self contained superhero story with some serious themes and darker tones filled with plenty of violence, this is one you should read.