I finished this just after surgery so I probably didn't retain everything.
Watchmen starts off with the murder of a superhero. That right there is absurd and flies in the face of what we know and love about superheroes! This hero looked pretty sketchy so we'll move on. We're in an alternate reality where Nixon is president and the Russians are about to declare war...nuclear war, no less. Superheroes have been outlawed, unless they work for the government and most are in retirement.
Watchmen follows the superheros who are left as they try to figure out who is killing them. We also have a nice subtext pirate story in here.
All in all, great comic, soon to be movie. I can see why the movie will be R as this is pretty violent, bloody and corpse-ridden.