When Euke's husband Taniyaja is kidnapped by mercenaries hired by a mysterious host to one of the Ra Taija - artificial intelligences controlling most of the Orion Spur- he's forced to go seeking memories of his lost past. He learns of his origins as a machine of war and of his role in the rise of the Ra Taija, realizing he owes one in particular, Sheuuno, a set of "Great Deeds" for abandoning his order. If he can complete all of these - and survive - he'll receive his husband back and finally be freed from the grasp of Sheunno. If he fails even one he'll lose him forever and be forced to abandon his honour as a Child of Humanity, though that might be a price he must consider once the web of politicking he's been dragged into has been revealed.