Poul Anderson 
Knight of Ghosts and Shadows 
A Flandry Book

The Terran Empire was faced with disaster. A turmoil of unrest on the planet Diomedes was the first spark that threatened to ignite a chain reaction of insurrection. All the attention of the ruling powers was centred on Diomedes – but Sir Dominic Flandry, bon vivant and interstellar troubleshooter, was one jump ahead. Through a highly unorthodox gambit, Flandry had learned that the Diomedean troubles were a red herring masking the real location of a deadly plan for a galactic civil war that would crush the Empire out of existence.Time was running out. Only Flandry had the knowledge that could prevent devastation. And when the real trouble began, Flandry was half a universe away.