Final answer:
Sophie and Agatha ended up in the Underground Library after their escape attempt on the backs of stymphs. They evaded wolves and fairies and found refuge there.
Step-by-step explanation:
Sophie and Agatha ended up in the Underground Library after their failed attempt to escape back home on the backs of the stymphs. The wolves and fairies tried to stop them, but they managed to evade them and find refuge in the Underground Library. This is a magical place where they continue their adventures in the book series 'The School for Good and Evil' by Soman Chainani.