This slim book is exactly what the title lets you expect, a kind of Diary of the character Jane Sagan. It’s a novelette, a ongoing inner monologue that describes Jane’s thoughts and feeling about many things, how she became who she is today, what she fears, what she loves and so on. John Perry (main character of Old Man’s War and her love interest) is used to highlight the difference between normal humans and the lives of the members of the special forces.
Some of Janes ramblings made me remember the one scene of Blade Runner, in the abandoned house where Deckard is hunted down by the Replicant Roy and when Roy saves Deckard and comes to peace with what he is. Replicant and Special Forces are alike, very short lives, but packed to the limit full of living.
TSD is, IMHO, a very fine piece of characterization that gives you a very good look into the mindset of Jane Sagan, I feel even a deeper look than you got at John Perry during Old Man’s War. It’s an impressive feat that makes you appreciate Jane as a character even more.