Cibola Burn is Book 4 of The Expanse.
Cibola, a word not previously known to me, is a name of the location visited by Coronado's disastrous expedition to find the city of gold.
This being The Expanse, however, we're far, far away from New Mexico; our expedition to find the city of gold has taken us to New Terra, a.k.a. Ilus, a.k.a. another planet that we get to through the gate.
We're now deep into The Expanse, of course, and many aspects have become familiar, but Cibola Burn does not flag, and picks up from the slightly-disappointing third volume to return to the excitement and thrills that the series is famous for.
As any thriller must, we need a good villain, and Cibola Burn's Murtry is as foul and despicable as you could possibly want.
And there are many other great new characters, including Elvi, the best biologist-nerd-heroine to come along in quite some time:
Scientific nomenclature was always difficult. Naming a new organism on Earth and even in the greater Sol system had a lengthy, tedious process, and the sudden massive influx of samples from New Terra would probably clog the scientific literature for decades. It wasn't just the mimic lizards or the insectlike fliers. Every bacterial analog would be new. Every single-celled organism would be unfamiliar. Earth alone had managed five kingdoms of life. Six, if you agreed with the Fityani hypothesis. She couldn't imagine that the ecosphere of New Terra would turn out to be much simpler.
But in the meantime, the thing living in her eyes -- in all their eyes, except Holden's -- wouldn't even officially be a known organism for years. Maybe decades. It would be officially nameless until it was placed within the larger context of life.
Until then, she'd decided to call it Skippy. Somehow it seemed less frightening when it had a silly nickname. Not that she'd be any less dead if she bumbled into a death-slug, but at this point anything helped. And she was getting a little punchy.
You know you're reading The Expanse when we get to "the thing living in her eyes". I'm doing my best not to spoil it any more.
By this point, I guess, you either love The Expanse, or you have no interest at all, but if you're in that first category, Cibola Burn delivers.