Evolution — Stephanie Diaz

Clementine's world is on the brink of destruction. An army of aliens from the distant planet Marden has arrived with a massive fleet of battleships, intent on finally putting an end to the war Kiel's old rulers initiated. With the Alliance headquarters reduced to rubble and one of the rebel leaders close to death, Clementine and her friends have no choice but to retreat to the Core to escape the alien ships attacking the Surface.

But safety in the Core means forming a temporary alliance with their sworn enemy, Commander Charlie. He's a ruthless man and a liar, but striking a bargain with him―his pardon in exchange for their help defeating the Mardenites―is the only way the rebels might survive the war. And Charlie needs their help too, for Marden's force is more powerful than anyone anticipated, with weapons and technologies never before seen on Kiel. Unless old feuds can be set aside long enough for a diplomatic solution to be found, all of Kiel's people will be destroyed, and everything Clementine and her friends have sacrificed in their fight for peace will have been for nothing.