THE MIMICKING OF KNOWN SUCCESSES by Malka Older is set on a human colony on Jupiter where all of humanity lives on a set of floating platforms connected by monorail tracks, now that Earth is uninhabitable.
Police investigator Mossa begins her new case: a university academic goes to a remote platform and then disappears. Did he swan-dive into the planet's center, and why? The investigation may be tied to the academic's research -- a major focus of study is the lost ecosystems of Earth, in hope of some day restoring them -- so Mossa seeks out Pleiti, an old schoolmate and romantic interest who's also an academic.
This was a likable mystery in a setting that you figure out as you go: there are
no exposition dumps explaining everything. Mossa has some Sherlockian quirkines
s, and there's a low-key romance between the two female leads.