Sometimes saving a world means rebelling against it. In an age long forgotten, nineteen hundred and eighty-three Seals were forged—magical disks placed around the world to repel the cosmic chaos beyond. In the centuries that followed, the Sentinels were tasked with protecting those Seals. For countless generations, they succeeded. Until now. At six years old, Shéana is recruited to the order of the Sentinels. A decade later, she displays powers unlike anything any Sentinel has shown before. When she feels the world stirring in pain, she knows the shield surrounding Tyronia has been breached. The great chain is broken. And the order of the Sentinels lies in discord. In the isolated village of Valdur, young Arth struggles to belong. Spurned by the other children, he ventures south to the endless mountains, and the strange barrier marking the edge of existence. The Final Horizon. Here he witnesses the impossible: a man emerging from beyond the veil—where nothing can possibly exist. A man Arth knows he must protect. Now the fate of two worlds rests on a knife’s edge. Only the courage of a village boy and the power of a fledgling Sentinel can save them. But to save their worlds, they must reject all they’ve been taught, leaving behind everyone and everything they’ve ever known.