The year is 2465 and mankind has spread to the stars. Not very quickly, though – FTL travel simply reduces the distance between stars to months, rather than years. This causes the occasional miscommunication between the various interstellar empires that have cropped up.
For instance, the Haldoran Combine has founded their Carson Colony on the planet of Carson, but they soon discovered that the Frithian Federation snuck in at some point and established their own colony on Carson. Probably have a different name for the planet and everything. The situation has been simmering for two decades now, and while there hasn't been open warfare between the colonies yet, they are getting tired of waiting for their parent empires to decide who gets the planet and are about to come to blows over the issue themselves.
Into this step the PCs, pilots of the Ambulatory Support Platforms that have gained prominence on these rough frontier worlds and recently signed on with a frontier trader that makes regular runs from Carson Colony's capitol of Cap City to the outer settlements. I'm sure that won't get them dragged into any shooting wars that might be upcoming. It'll be fine.