A Court of Thorns and Roses ends with Feyre saving Tamlin and Prythian from the villain Amarantha, and Sarah J. Maas' heroine frees them by solving the faerie queen's riddle. When Amarantha takes Tamlin and the other High Lords Under the Mountain, it seems like they'll never escape her clutches. Feyre ventures Under the Mountain to help Tamlin, and she faces a series of tests in order to save the man she loves. Amarantha throws Feyre into dangerous situations, even pitting her against a Wyrm, and she also takes any opportunity to mock her illiteracy and mortality.
https://screenrant.com/court-thorns-roses-amarantha-riddle-answer-love-explained/