Zion — Katharine Kerr

Over a hundred years ago, the inhabitants of the planet Zion exiled a disruptive group of religious fanatics to its sister planet, Ninva. The exiles and their descendants have never stopped brooding on revenge. After a brutal invasion, they finally get their opportunity for bloody vengeance as the Zion falls to the fanatics. Only one person manages to escape Zion. Andra Godluv turns to the planet Thorn and to beg for help from the Rim Council and their battle group. Even if Thorn responds can the Thorn fleet even get to Zion in time to make a difference since Zion has been cut off from the Rim ever since its one access shunt was destroyed? Dan Brennan is tasked to find a new, faster route for the fleet. But even if he succeeds, Thorn itself is struggling with multitude of problems, including new threats from the terrorist group, The Bloody Vigilantes, thought to have been eradicated.