This book is almost two separate stories put together -
The first is Miles's first assignment out of the academy, a post as a weatherman in a desolate (and rather chilly) location. It is meant as a test to see if he can shake off some of his insubordination, and if he passes this test, he will be awarded a post on the Barrayaran military's newest ship. He deals with a mad superior and obviously (and unsurprisingly) fails the test.
The second part of the book places him back among his Dendarii mercenaries, as part of an assignment by Imperial Security's head, Illyan. While he succeeds in the spirit (one would say) of the orders his superior on this mission had, he gets himself into a rather complex political situation. I liked this book, because it was fast paced and pretty complicated in some parts, with more twists than any standard novel. I really liked the development of the emperor Gregor as well and I look forward to where the story goes after this book.