Cibola Burn

Cibola Burn by James S. A. Corey, 581 pages.

After the Ring Gate opened in the third book of the Expanse series, the fate of humanity has shifted. People from Earth, Mars and the Outer Planets are all heading for the new frontiers and getting ready to take their chances on one of the 1300 gates to see and claim the planets those gates lead to.
One planet quickly becomes the focus of a violent disagreement between a group of refugees from the Jovian moon Ganymede, who snuck through the gate, and a corporate expedition whowant  claim the planet as their own. The Rocinante, with its crew of Nagata, Holden, Burton, and Kamal, is nearby enough for Fred Johnson of the OPA (the Outer Planets Alliance) and Chrisjen Avasarala of the UN to both ask them to mediate the disagreement.
James Holden finds he has another reason to head to the disputed planet, his dead friend, Detective Miller, speaking on behalf of the protomolecule, wants a look at the machinary under the planet.
It all sounds convoluted and complicated, but by the time this is over, you're over 2,000 pages into the series and it all makes sense. At the core of this book, as with many in the series, is the battle between those who are trying to do the right thing, and those who are in it for their own gain. Good, solid characters and a fast-paced, interesting story, make it all work; the Expanse books are always a joy. Bobbie Draper shows up briefly, and new recurring characters, Elvi Okoye, and Fayez Sarkis, make their first appearances.