From the Publisher's website:
The Dark Eldar are a plague upon the Koronus Expanse. Any who cross the Maw and sail the void of the Koronus Expanse learn to fear the wicked silhouettes of their ships and their seemingly endless cruelty towards all life, including their own. Only vigilance and firepower keep the worst depredations of these terrible raiders at bay. Do you have the courage to face them in the name of the Emperor?
The Soul Reaver, an adventure in three parts for Rogue Trader, presents a chance for daring Explorers to look deep into the twisted heart of Dark Eldar society in the Koronus Expanse, where they’ll attempt the greatest heist of their careers! This, along with a new playable xenos Career Path, the Dark Eldar Kabalite Warrior, offers players useful content long after the adventure concludes.