From the synopsis on the Baen website:
“Ten soldiers on convoy in Afghanistan suddenly find themselves lost in time. Somehow, they arrived in Earth’s Paleolithic Asia. With no idea how they arrived or how to get back, the shock of the event is severe. They discover groups of the similarly displaced: Imperial Romans, Neolithic Europeans, and a small cadre of East Indian peasants. Despite their technological advantage, the soldiers only have ten people, and know no way home. Then two more time travelers arrive from a future far beyond the present. These time travelers may have the means to get back, but they aren’t giving it up. In fact, they may have a treacherous agenda of their own, one that may very well lead to the death of the displaced in a harsh and dangerous era.”
Honestly the book rather defies description, it’s not really an alt-history, it’s certainly time travel, but is it an adventure? Well sort of, while highly entertaining, those looking for lots of daring do and explosions and the usual carnage from Williamson will be sorely disappointed. The soldiers have only a basic combat load of ammunition so going a conquering and to conquer is out of the question. The book focuses more on how 10 average soldiers (and yes for the record, it is entirely possible that any random group of 10 soldiers will have all or most of the skills in the novel) cope with finding themselves in a situation for which they were never trained — indeed for which no one could be trained — and learning to cope with the fact that they may never get home. The characters are realistic, three dimensional and real to the point that there are some you really hope will meet a bad end.
From a sheer craft standpoint it’s easily Williamson’s best work. However, I did find the ending a bit of a Deus ex machina, but plausible within the confines of the story — and well set up for the sequel I’m reliably informed is coming.
The unedited eARC is currently available from Baen eBooks and the hardcover is scheduled for May.