Star Wars Legends: Dawn of the Jedi - Into the Void

On the planet Tython, the ancient Je’daii order was founded. And at the feet of its wise Masters, Lanoree Brock learned the mysteries and methods of the Force—and found her calling as one of its most powerful disciples. But as strongly as the Force flowed within Lanoree and her parents, it remained absent in her brother, who grew to despise and shun the Je’daii, and whose training in its ancient ways ended in tragedy.
 
Now, from her solitary life as a Ranger keeping order across the galaxy, Lanoree has been summoned by the Je’daii Council on a matter of utmost urgency. The leader of a fanatical cult, obsessed with traveling beyond the reaches of known space, is bent on opening a cosmic gateway using dreaded dark matter as the key—risking a cataclysmic reaction that will consume the entire star system. But more shocking to Lanoree than even the prospect of total galactic annihilation, is the decision of her Je’daii Masters to task her with the mission of preventing it. Until a staggering revelation makes clear why she was chosen: The brilliant, dangerous madman she must track down and stop at any cost is the brother whose death she has long grieved—and whose life she must now fear.