I think I'll go with the consensus that A Circus of Hells is a weaker entry in the Flandry series. After the Starkand intrigue and a successful stint through intelligence school, which is elided, Flandry is back on the frontier as a scout pilot and junior intelligence officer.

A local gangster suborns him into checking out a rumored lost automated mining station, with the catch that one of the gangster's agents will be aboard. Flandry insists on a pleasant and willing female companion (ugh), but the beautiful and sexy Djana has been suborned by yet another faction.

The criminal intrigues are dropped for a straightforward survival story, when the automated mining station is revealed to have gone rogue and created an ecosystem of hostile robotic creatures, which down and damage Flandry's scout. He and Djana cross a deadly moon with a chess theme to the central hub, which is repaired in a few sentences. But then Djana betrays him, and it turns out the other faction are the expansionist Mersian empire. Gasp, shock.

Flandry and Djana are captured and taken to yet another remote planet, home to a combination Mersian military outpost and xenological research base. The planet has an extreme orbital eccentricity, with annual variation between boiling jungle and glacier covered ice ball, and an ecosystem to match. Djana is suborned by the local Mersian commander, who trains her in unspecified psychic powers, while Flandry joins the scientific mission and plots a daring escape.

Any of the stories is fine on it's own, but there's really too many, and the rogue robotic ecosystem is both the most interesting part and underbaked. Djana's characterization is painfully retrogradedly sexist, and Flandry as one of a few active and decent men in a decay empire is reduced to a tactically clever but strategically void blockhead.