It's based on a graphic novel over 20 years old. Did you know they kill the monkey at the end of "King Kong"? And that 'Rosebud' was a sled? Or that the ship sinks in "The Titanic"? Anyway, it is easily the most celebrated graphic novel of all time, and you should all read it, then go see the movie 1000 times. The trailer is below, along with a link that breaks down the trailer scene by scene. Do I seem excited?
According to IMDB...the only place I could find that doesn't 'spoil' the movie...
In a gritty and alternate 1985 the glory days of costumed vigilantes have been brought to a close by a government crackdown, but after one of the masked veterans is brutally murdered an investigation into the killer is initiated. The reunited heroes set out to prevent their own destruction, but in doing so discover a deeper and far more diabolical plot.
Who watches the Watchmen?