Doing Time

Fans of the St. Mary's series will know the Time Police as generally stick-up-the-bum humorless jerks and sometimes just horrible people, but this first entry in a subseries about the Time Police presents their organization and officers from a kinder perspective which gives insight into the good reasons for their authoritarian enforcement culture.

This is a really enjoyable adventure which broadens and deepens the St. Mary's worldbuilding; however, I think that having read the books in the main series will make it far better than a reading by someone who is unfamiliar with the backstory and worldbuilding.