There’s a Demon in the Eastern Palace

To repay a meal, a thousand-year-old fox spirit possesses Jiang Zhanzui, the illegitimate daughter of a chancellor who died unjustly, and helps her avenge her murder. She takes on her stepmother and torments her half-sister, then easily becomes the crown prince's consort. Her revenge is finally within reach. But what's the deal with this man named Meng Hegui? He knows who she really is, yet never bats an eye and constantly works against her!