Twenty‑seven‑year‑old bankrupt book restorer Mina Clarke awakens the special ability to understand dragon oaths while repairing an ancient parchment ledger. Her interpretations revive long‑buried ancient debts and leave her detectable Reader’s Mark. Facing Dragon Queen Vesper, who weaponizes old debts for royal power, Mina and exiled royal Sable evolve from mutual exploitation to genuine trust. They investigate corrupted blood‑line debts, reject fighting old tyranny with another, push for debt‑system reform, break free from power shackles, and build an equal romantic bond.