It’s not an overstatement to say that it would be almost impossible to appreciate the modern state of the graphic novel format without reading Moore’s work. The outstanding quality of his output since the early ’80s has continued at its unparalleled level ever since.

Moore turned the superhero universe on its ear with 1986’s Watchmen, probably his most seminal work. Watchmen was a reworking of the comics of the industry’s heyday in the 1940s and 1950s. But in Moore’s vision, superheroes battled alcoholism, sexism, impotence, love, politics, and isolation just like everyone else in the world. No longer were heroes aloof and superhuman; Moore put the emphasis on the human and laid his characters bare for all to see. Added to the mix were a backdrop of Cold War-era fears and threats of nuclear aggression and, to boot, a murder mystery. The story is intense and sprawling, as well as perfectly complemented by the intricate artwork of Dave Gibbons.
 
No simple synopsis could do this sprawling story justice. It begins with a murder mystery, delves into obsession and the dark psychology of the mind, takes a respite with a parallel story of an evil pirate ship, branches off into science fiction, and stays compelling with a serious warning about the power of idolism and the need for simple humanity. At least, that's one way to read it. There are more. The work is complex enough to sustain multiple takes.
 
If you haven't read Watchmen, do it now before the movie. If you already have read Watchmen, do it again. There's stuff in there you've forgotten and you'll appreciate the refresher.