Worlds on Edge - The Backworlds, #5

In the far future, humanity settles the stars, bioengineering its descendants to survive in a harsh universe. This is the fifth book in the science fiction series, The Backworlds. A space opera adventure. War is coming. A horde of merciless aliens poise just beyond the Edge. In a matter of weeks they will devour the worlds. Racing ahead of the apocalypse, Craze returns to the Backworlds to warn them and plan a defense.
Only he can't go home. Banned from Pardeep Station, he must wage a more urgent battle. His moon is under siege, and his friends are dying. Bad things come in threes, and the galaxy is no exception. An old enemy returns, attacking moons and defenseless globes, leaving a wake of destruction. Worse than that, they threaten to join forces with the alien horde. Defeat seems inevitable. Craze may not be able to stop it.
Yet home is worth the fight.