In the ancient world of Solarune, siblings Caelus and Selenea spend their days deciphering sigils and wandering hologram museums until Caelus awakens Aetheris, a rare gift that lets him pinpoint any being in the universe. Recruited by the charismatic monastic leader Orpheus to hunt galactic criminals, Caelus rises through the ranks while Selenea joins his fearsome First Battalion.
But when Selenea defies orders to annihilate an innocent civilization, she uncovers Orpheus's true design: to snuff out the stars and remake existence in darkness. Branded traitors, the siblings forge a ragtag rebel fleet, racing from volcanic wastelands to icebound tundras, turning magma bombs, avalanche traps, and asteroid armadas against Orpheus's unstoppable Fractals, rips in space that carry his armies across light-years in an instant.
Caelus must face Orpheus, and the celestial Valthorim, ancient watchers torn between creation and oblivion, hold the fate of every planet in their colossal hands. The universe trembles on the brink; only the bond of two brave siblings stands between hope and total darkness.