From FreeSpace Wiki
As the Alliance wages a brutal war beyond Regulus, the GTVA 6th Fleet in Ikeya vanishes after a urgent distress signal is sent.
With communication relays within Ikeya systematically destroyed within moments after; the Alliance is left with the fear of a second war front.
Under the vigil of the Hecate-class destroyer GTD Morgain, a small task force is sent to discover the fate of Ikeya.
As a wing commander of the second joint Terran-Vasudan squadron, the Scythes of Twilight, you must pilot your vessel into darker, more desperate realms of the universe; to save the Alliance... from itself...
The original version can be found under the "Downloads" section of the original site. An upgraded version, with bugfixes and Lightspeed's backgrounds, can be found here.