Valerian 15 - The Circles of Power

Broke, without a job, their ship almost a scrap heap, Valerian and Laureline are stuck on Rubanis, unable to pay for repairs. So when a trio of old acquaintances introduces them to the head of the local police, who is looking for independent agents for a risky but well-paid mission, they accept readily enough. But Rubanis is the most corrupt planet in the entire galaxy. How are they to find out who really holds the reins of power there?