Yes, that Kevin Costner.
I still can't actually decide if I liked this book.
So first off, the good stuff: The format is hard to pin down, almost 50/50 written text and comic book style panels. Like some panels inserted here and there like spot illustrations, then sometimes pages and pages or even most of a chapter in comic book format. Then chapters of almost entirely text. It seems to switch back and forth however the authors felt would best convey the section at hand with no other pattern to it, and honestly I really liked that format of storytelling. The media serves the story, and some stuff really does work better visually where other parts are better told in text. The fluid switching back and forth did take a little bit of getting used to but I liked it so much that if I were ever to write something like a novel I can easily see using this method myself.
The whole thing very well captures the feel of the 1920s/30s pulp adventures, an era I'm pretty fond of. It's set around World War I, a very Indiana Jones-esque escapade that ranges across multiple countries where it's not always quite clear who are the good guys and who might be villains in disguise. Unfortunately it also carries the offhanded hints of racism one expects from pulps of the era. As somebody who reads older works, I'm willing to allow it in those books even in reprintings. As a newer book, there is ample opportunity to handle racism differently, to either include it as a sign of the times while also making clear that it is objectively bad, or just not include it all. There are plenty of modern approaches that could happen to acknowledge casual slurs while they may be period-appropriate are also not condoned by the modern authors. I did not see any signs of that approach. They're just... there.
The plot itself is wild and complicated and I'm not sure I can go into much detail here without giving things away, but suffice it to say this group is looking for the fabled land of Shambhala but the passageway to get there is not at all what you would expect.