Having been washed out of Earth's Military Academy on purpose so that he wouldn't have to go into State Sec, Lon winds up on Dirigent, a planet whose primary business is supplying weapons and mercenary armies to the galaxy at large. He's granted a commission as an officer cadet, but the DMC does not allow you to command until you've seen a tour of duty. It's a waiting game until the DMC gets a contract for a battalion-strength job to put down a rebellion on some rock in the middle of nowhere.
Things get complicated, fast.
The books cover a broad span of years, following Lon as he rises from an Ensign Newbie to a Colonel Badass. They've received critical praise for their realistic depictions of life in a military unit (Shelley was a US Army veteran).
This series provides examples of the following tropes:
- Asskicking Equals Authority: The Dirigent Mercenary Corps does not allow you to command until you've seen combat, so in the field an officer cadet is a grunt like the enlisted.
- Idiosyncratic Episode Naming: Each book is named for the rank Lon holds in it.
- Kinetic Weapons Are Just Better: Hand-held energy weapons exist and are prized for being basically silent, but the standard weapons are chemical firearms.
- One-Product Planet: Dirigent's industries are built around the DMC, and their primary exports are soldiers and guns.
- Private Military Contractors: The DMC has strict limits on what jobs it will take and the soldiers pride themselves on professionalism, but they're in it for the money.
- Standard Sci-Fi Army: The DMC provides mainly light infantry, although they also use their drop ships for close air support.
- Universal Universe Time: Dealt with on Dirigent by lengthening the second to make a Dirigentian day 24 hours.
- Unproblematic Prostitution: One of Lon's fellow cadets is engaged to a prostitute at a brothel, and recommends her to all his friends. The implication is that on Dirigent it's a legal, regulated profession. Lon still isn't comfortable with it, although it's more having a hangup about not sleeping with another man's fiancee.