Doc Roberts is a privateer working for the Alliance military to destabilize shipping, trade, and the planetary governments of the Coalition of Free Worlds, to sway them to accept Alliance protection. He does this by raiding colonized worlds, and hijacking freighters loaded with trade goods.
With the Alliance, failure is not acceptable. Those who fail are sent to reeducation camps to have their minds wiped and reprogrammed with a submissive personality, then they are placed in a control collar, and sold at auction to the highest bidder. Leaders who fail are publicly executed by hanging.
Doc is given a job, stealing the Mindharp of Tombaku. He only has a limited period of time to get it and return. He learns that he is not the first one given this mission. If he succeeds, it is the end of the Coalition. If he fails... he loses his life.