I listened to the audio version of the book and really enjoyed it. The setting is a very caste driven military setting that is fighting a war against heretics. When Captain Kel uses unusual mathematics to defeat heretics she comes to the attention of her superiors and is tapped to come up with an idea to recover a space fortress. Her idea is to bring back a dead general to take the fortress. General Shuos Jedao intelligence has been upload into a black cradle and is very occasionally brought out to solve hard battles, but he is crazy and was sent to black cradle for slaughtering his own troops. Kel has Shuos upload to her brain and he provides good advice to her for the war even though she finds herself liking him. There is more to his backstory than she was told, and the unfolding story is great.
I think I’ll keep with this on audio for my next long car trip.

I think I’ll keep with this on audio for my next long car trip.
