The Imperial Legate

In 2754 the Galactic Empire extends among the stars, dominating thousands of planets.
Nothing could resist the expansion of the human race, that submitted every new alien race met in the galaxy with the military force of its space Legions.
But a simple request for help sent by a frontier outpost hides a terrible threat: the invasion by an alien, unknown enemy. A new, strong race suddenly upsets the same Empire foundations by a massive attack.
Just when the situation seems desperate, Caio Aurel...