The Chronicles of Riddick

May 2004 Del Rey mass market paperback, Alan Dean Foster (Splinter of the Mind’s Eye). Richard B. Riddick has been in hiding for five years, evading bounty hunters and mercenaries sent to capture him. After killing a crew led by Toombs and stealing his ship he heads to New Mecca in the Helion System, after Toombs reveals his bounty originated there. Riddick is reunited with Imam, the man previously rescued. Imam believes Riddick is a Furyan, a race of warriors long thought extinct, and wants to know about his homeworld and if anyone other than himself is left. Imam believes Helion Prime is the next planet to be conquered by a mysterious force crusading across the stars. Aereon, an Air Elemental, identifies the army as the Necromongers, religious fanatics who seek to convert everyone and kill those who refuse. The Necromongers attack, and take control of the capital in a single night. In the battle, Imam is killed and Riddick escapes.- Wikipedia