Thomas DePrima - Castle Vroman (A Galaxy Unknown, Book 6)

From inside a giant asteroid, hundreds of light years from Earth, Admiral Jenetta Carver is beginning to look forward to a trip home, and finally receiving command of her own ship. Her five-year tour of duty as the Base Commander of the Stewart SC Base is nearing an end, and the ship carrying her replacement has been underway for more than a year.

However, when the GSC destroyer carrying Admiral Vroman is attacked just a few light years from the base, her plans are quickly forgotten. Rescue ships arriving at the site the next day find only corpses aboard the Lisbon, while a severely damaged freighter with a dead Tsgardi crew floats nearby. There's no sign of the admiral, and most of the SC crew is missing.

The Milori Military Forces, unsuccessful in their first attempt to defeat the Galactic Alliance and annex its territory, are preparing for a second assault. Emperor Maxxiloth has decided he won't be embarrassed a second time and sends every ship available in his empire as part of the new invasion force.

Months later, a shuttle touches down on a primeval world far inside the Frontier Zone, where Admiral Vroman and the senior officers from the GSC destroyer Lisbon are to be marooned by their Milori captors. As the rest of the crew is being shuttled down to the surface, the officers quickly draw up a plan of survival. Left with only the most basic of supplies and equipment, the spaceship crew must learn how to exist in a hostile, planetary environment.

While the forces at Stewart are preparing for an imminent attack by the Milori, the crew of the Lisbon is learning that they have some rather large and particularly nasty neighbors with voracious appetites and predacious habits.