From the back of the book:
Death stalks the galaxy. The dread Charon, destroyers of worlds, killers of galaxies, have found their way into realspace. If they are not stopped - and soon - the Rebels' galaxy, too, will die.
In a remote, little traveled corner of the galaxy, the Alliance safe-world of Stronghold floats serenely against the bloody backdrop of Rebellion and Empire. Here, families of Alliance warriors hide from Imperial attack.
But something has gone wrong on the safe-world. Terribly wrong.
There has been no contact with Stronghold for weeks. No comm reports, no ship traffic. Nothing. It is as though the entire planet has vanished. Six Alliance personnel race to Stronghold to find out what has happened to the planet - and to their friends and loved ones hiding there.
Six Rebels - against the Invasion!