Princess Asteria of Soria has been training all her life for the Tournament of Day and Night-a brutal and deadly competition started by ancient gods where countless bloodthirsty warriors are fighting to destroy their enemies. Without the king's permission, Asteria makes a bargain with the gods and binds her life to the Tournament. As punishment, the Sun King makes a deal with the enemy kingdom Luna-the Kingdom of the Moon-and Asteria is betrothed to one of the warrior princes.
Asteria vows to continue her participation in secret, willing to do whatever it takes to become the next Victor and prove her eligibility to be crowned Queen of the Sun. There is only one problem-Prince Star, a Victor of multiple games, is back in the Tournament with scheming plans Asteria is dragged into with no way to escape.
The Tournament quickly turns out to be nothing like Asteria expected, and forced to ally with the enemy, she must do whatever it takes to win-even if it means sacrificing her heart and kingdom.