This is the sequel to Old Man's War, but it's more of a tangential sequel. As has been pointed out at great length, one does not REALLY have to have read OMW in order to get the point of it. But Jane Sagan from the first book is a main character in this one.
Anyway, this book focuses on the "Ghost Brigades." In this universe, Earth has been quarantined from the rest of the universe and kept in the dark as to what the Colonial Union forces are up to. The elderly are recruited to join the military, get transferred into new militarily-built bodies, and fight in order to preserve Earth's colonies from the other species fighting for territory. But what happens if an elderly person dies during the 10-year period between signing up and joining up? Instead of being able to transfer consciousness into a cloned body, the cloned body gets souped up to the gills and the new "Special Forces" soldier wakes up to find themselves in an adult body. They can function as an adult immediately, despite being mere hours hold.
At the beginning of the book, it's discovered that three alien species have gotten together and are planning war against the entire Colonial Union. And that Charles Boutin, a CU scientist who's worked on consciousness transfers and BrainPals (the in-head computer in soldiers), has turned on his people and gone to work with the aliens. Left with nothing but a cloned corpse of Boutin and a recording of his consciousness, some generals get the idea to clone a body of Boutin and then try to get his consciousness working within it. Maybe then they can find out why he went turncoat.
Alas, the consciousness transfer doesn't really work, and the new body is turned over as a soldier in the Ghost Brigades and given a name, Jared Dirac. He goes through two weeks of training, bonds (and screws, hee) with his fellow soldiers, and gets into fighting battles. But after one particularly horrible mission, he starts to remember things that Boutin knew, and soon figures out (or so he thinks) why Boutin did it and where he's gone. Then he and his squad go in search of Boutin...
It's a pretty gripping book, and I'm sorry I read it so fast. The mission that sets off Dirac is heartbreaking and shocking on so many levels. And the ending is good all around, especially some of the final maneuvers. I will be looking forward to the next book, The Last Colony.
Four stars from me.