The story for The Churn is entirely Earth based and gives you a pretty decent description of what the average life in a crowded, metro city, is like in the Expanse Universe. The city, Baltimore, has given way to a multitude of crime bosses, and organized black markets. There are multiple bosses who each keep a "family" of personal guards that operate the smuggling of goods, illegal memory implants, weapons smuggling, cybernetic implants etc. The story takes place over the course of about two days.
The main characters in The Churn are all members of varying degree's of the crime world.