Harbinger - David Mack A new Star Trek series, set in the early period of Kirk's command of the Enterprise.
The action focuses on Starbase 47, also known as Vanguard. Situated between Klingon & Tholian space, it's build was significantly fast-tracked by the UFP for reasons unknown.

It now houses a mix of alien races both as crew, civilians and tradespeople; imagine an early Deep Space Nine/Terok Nor.

It takes a while to get used to the new crew as they're introduced. The Enterprise makes a stop there which lets Kirk size up Commodore Diego Reyes and some of the other key characters.

There are several threads to the story, as the Klingons, Tholians and UFP jostle up against each other, possibly heading for war.