In the Stormy Red Sky, Paperback/David Drake

Daniel Leary is Cinnabar's most successful space captain; his friend, Lady Adele Mundy, is its most efficient spy - but they've got their hands full this time as they face: a vengeful Cinnabar Senator, a boy ruler of a star cluster who thinks he's a god, a world of slaves and escaped slaves, and an almost indestructible enemy base.