Ship of Destiny

Sam Bitka, a naval reserve officer, is recalled to wartime service and soon earns a reputation for aggressive tactics and insufficient deference to his academy-graduated superiors. His latest run-in with authority earns him a transfer to command of an armed transport, USS Cam Ranh Bay.
When a mysterious alien probe materializes from Jump Space and remotely reprograms The Bay's star drive, Sam and his crew begin an involuntary voyage that takes them three thousand light years out of known space, across the galactic rift to the Sagittarius Spiral Arm, and into the heart of an ancient, previously unknown civilization-the first encountered by Humans and the other five races of the Cottohazz-Stellar Commonwealth-in over a century. The genetically altered immortals known as the Guardians, a race so old they do not remember their own origins, soon turn murderously violent.
Now Sam and his crew must elude capture by the Guardians, find some means of reprograming their own star drive, and then return to the Cottohazz with the news of a powerful new civilization bent on their destruction. But they may also be carrying the secrets of the origin of their own star drive and of the path to immortality.