Therefore, all my books have started with the League of Peoples: an alliance of super-powerful aliens who are happy to let us humans (and other such primitive species) do whatever we like… provided we don’t cause trouble. Specifically, the League doesn’t want homicidal creatures leaving their home star systems and traveling elsewhere — that’s like letting a disease spread. If you do have murder in mind and you try interstellar travel, the League infallibly executes you the second you "cross the line" from one star system to the next.
This ever-present threat has influenced much of the action in my first three novels, but oddly enough, the League never directly killed anyone in those books. That all changes in the fourth book, Hunted. The League executes almost everybody on a navy starship, and the single human survivor has to find out why.