Like SPIDER-MAN: BLUE and DAREDEVIL: YELLOW, HULK: GRAY is a retelling and expansion of the title character's origin story, a filling in of the gaps, I guess you could say. Jeph Loeb's script and Tim Sale's art tells a story that takes place in the first 24 hours or so after Dr. Bruce Banner was caught in the gamma bomb explosion that transformed him into The Hulk. Or, as Loeb puts it in an afterword to this trade paperback that collects the mini-series, between THE INCREDIBLE HULK #1 and THE INCREDIBLE HULK #2.
Plot-wise, there's not much to this tale. General Thunderbolt Ross tries to capture or kill The Hulk. Rick Jones helps The Hulk. And The Hulk tries to get to Betty Ross, who he senses somehow that he loved when he was still Bruce Banner. Those of us who are long-time comics fans have seen variations on all those things too many times to count.
This is the first Loeb/Sale collaboration I've read that I found to be something of a disappointment. There's nothing really wrong with it, but it just didn't evoke the same sense of nostalgia in me that their other stories revisiting the early days of some iconic characters. I didn't care for
's versions of The Hulk or Rick Jones. They both just looked too goofy for my taste. I will say, though, that Sale does a good Thunderbolt Ross, and the first appearance of Iron Man (who plays a small part in the tale) in the original golden "tin can" armor did send one of those nostalgic thrills through me. It's a shame Loeb and Sale didn't do a similar mini-series about Sale (Maybe they did and I'm just not aware of it; I was away from comics for quite a while.) Iron Man.
If you're a big fan of The Hulk, or if you remember those early days at Marvel with fondness, HULK: GRAY is certainly worth reading. It's just not up to the high level that its creators achieved in their other projects.