The unkillable princess - Taran Hunt

Having escaped the dangers of the Nameless with the Philosopher Stone data, Sean thought his troubles were over. Until he gets a call for help from his sister Brigid--his long-dead sister.

Brigid is sparse on the details, but she needs Sean to go to the Republican city of Illin to retrieve something called a "Purifier" for her. Reeling from the desperate hope that his sister is alive, Sean aims for Illin, dragging his new companions, Tamara Gupta formerly a Republican soldier, and Indigo, the Minister responsible for the destruction of Sean's home, into the fray.

But as usual, Sean hasn't quite thought this through. The three of them are all wanted by Republican authorities, and Illin happens to be on the same planet as Sean's old friend Senator Ketel. Y'know, the one who blackmailed and nearly murdered Sean. With every move Sean makes he discovers more intrigue, more people on his tail, and more ways that his little adventure could be the spark for war between the Republic and the Ministers. And to what end? Is it really his sister, a chance for family, and safety, on the other side?