A powerful but hidden heir with ancient, pure divine blood has secretly eliminated assassins with devastating flames. His family's chief guard, Henrik, investigates the attack, unaware of the heir's true power. The heir, forced to conceal his abilities to avoid fatal backlash before his 18th birthday, bides his time until the Divine War, when his powers will unseal. Meanwhile, the Princess of the House of Sol, seeking to escape a forced marriage to a rival underworld prince, impulsively proposes an engagement to the heir, who is widely seen as a powerless mortal. Her reckless act, meant as an insult to her suitor, unexpectedly drags the hidden heir into the open, setting up a confrontation that could expose him far earlier than planned.