The blurb is under the cut for the particularly spoiler-wary.
Before they united in the fight against evil, Rey, Poe and Finn led very different lives. Rey was a lone scavenger on the desert planet of Jakku. Poe was a pilot for the Republic. And Finn was only FN-2187, a promising but reluctant stormtrooper. These are their stories. This is what happened before the Awakening.
The part about Finn was more or less confirmed by the latest trailer, but was also the subject of an earlier rumor. (Note: Link contains possible spoilers above and beyond the name issue.)
Poe being a pilot for the Republic – before the Resistance – is new. Between this and the hints in some of the Journey books, it’s looking very likely that there is a New Republic in this new GFFA after all, and the Resistance is a separate – perhaps splinter – group.
Greg Rucka’s Before the Awakening is a companion book to the Journey character novels (Moving Target, Smuggler’s Run and The Weapon of a Jedi) that came out on Force Friday. It’ll be out with the film on December 18th.