Before disappearing, Proteus predicted a threat was approaching the solar system. Something big. But when a year goes by with no attack, Lunar Jones is forced to focus on the here and now. Phobos and Deimos both need new riders. More recruits than ever are trying out for their now-famous crews. And in all of that chaos, Lunar is busy preparing with Dread for the Solar Summit--a meeting between the planetary dragons that happens once every five hundred years. He's so busy he almost flies right by the first clue. A derelict ship between Earth and Mars.

The crew has gone missing. When Lunar stops to investigate, the evidence points to an attack by nine creatures. After the attack, they took flight with one enemy aimed at each of the nine planets. It doesn't take long before the entire solar system is locked in battle with creatures called void dragons. An undead enemy that proves very difficult to destroy. Worse, their arrival signals the approach of something that would make the light of even the brightest stars tremble: a black hole. If Lunar and the Dread Knights want to save their world a third time, they'll have to forge new alliances, summon new powers, and be willing to sacrifice everything.