Elijah Snow, Jakita and the man known as "Drummer" are the travelling troubleshooters of the Organization known as "Planetary". Now, they have come to Gotham City on the trail of a man known as John Black. Black seemed ordinary, but his parents were killed when he was young, and it triggered his psychic power of reality warping. Within an area, he can bring himself, and any other people near him, into a different reality, or bring things from other realities into our own. Through use of his powers, he's inadvertantly slaughtered a number of people.
Elijah Snow has seen this sort of thing before, when several multiverses crashed together and fused the bodies of the people living in them together, quite messily. The three agents are assigned to work with Dick Grayson and Jasper, both assigned to the local office. Snow, though, has no good opinion of either Gotham City or the local members of Planetary, especially Jasper, a Green-haired, white-faced and purple-lipped man. It's he who deduces John Black's reality warping powers, and he abandons the local men to try and track down John Black himself, along with Jakita and Drummer.
But when they confront him in the back Alley known as "Crime Alley", the shock of being attacked makes Black use his powers to send them all to a different Gotham, one where a man known as "Batman" is alive and well. As Elijah Snow and Drums attempt to grapple with Black and bring him back to their world and dimension, Batman sees the commotion and assumes that they are all responsible for men Black has killed and ends up attacking Jakita when she resists his attempts at "taking them in".
But as Drummer is nearly taken out by the shock of switching realities (he can read the world's information streams, and being shunted from world to world is horrible for him. But as Snow tries to reasn with John Black and make him see that he needs to be contained for his own good and the good of others, he continues switching worlds on them, causing the Batman that Jakita is fighting to change along with the worlds, from the 60's era TV/movie Batman, to several iterations of the comics Batman. Finally Jakita is able to deiver a knockout blow, but Batman isn't out for long, and when he comes to, this version of him is able to sympathize with John Black, and perhaps ease a little of his mental trauma. But can Black retain enough sanity to return them to their home dimension?
I have only read one book of Planetary, so I didn't know the characters very well, and since I read it a good, long time ago, well, what I remembered about Planetary and the other characters is vanishingly small. But Planetary wants to uncover the secret history of the world, and sought out Elijah Snow because they needed his detective skills. But those skills aren't all he has- he can manipulate heat and cold and seems to be ageless/immortal. The fact that he has a high level of detective skills sort of make him like his own world's version of Batman, albeit with one sort-of superpower. And this made it amusing that he seems to consider Batman with something like scorn.
I really found the comparisons of the different Batmans (Batmen?) amusing, as the script of the comic is included afterwards, presumably so that readers who aren't familiar with all the different iterations of Batman can figure out who is who. I really laughed when I recognized the Adam West Batman (most noticeably for the helmet and how he calls everyone "citizen" and carries "Bat Female Villain Repellent Spray") and some of the more interesting iterations, like the Facist Dark Knight Batman, the 30's and 40's vigilante Batman (who carries a gun despite his own parents being gunned down), and it's the final, gestalt Batman, who manages to connect with John Black and bring some sort of closure to his life.
My biggest problem with the graphic novel is the high cost of the book versus the short version of the story. The script pads it out to "usual" graphic novel length, but the story is almost over in a blink. I, and I think a lot of readers will feel that the story should be longer- not because it's missing anything, but just that you want it to go on and have more happen than just a fairly short encounter with Batman that mostly consists of Jakita fighting Batman.
This is a great story and well-told, but the high price of the graphic novel makes it feel like a horrible value for the money. Even with the included script, it just feels unnecessarily padded and expensive. The story is great, and the art is also great (Cassaday can ape the styles of other artists and still retain his own for the rest of the characters). But the price... and I don't mean to keep harping on that, but one issue for $22 is just not a good deal, even with the script. Highly recommended for the story, but not recommended at the price.