The greatest swordsman on Earth has never had a real fight.

Sebastian Kern has won everything there is to win. Medals, fame, fortune, and an undefeated record have made him a legend—but also left him empty. Then a silver-skinned alien envoy appears with a desperate plea: a tyrant known as the Cinder King is coming for the Federation of a Thousand Worlds, and every champion who has faced him has died.

Sebastian is taken across the galaxy, handed a sword from Earth's oldest legends, and asked to do the impossible.

But the duel that waits for him is not a sport. It is not a performance. It is a battle for the fate of worlds—and for the first time in his life, Sebastian Kern may finally discover what it means to fight for something that can be lost.