Scott Hawkins’ 2015 The Library at Mount Char is a standalone contemporary fantasy.
Retrieved from certain doom by neighbor Adam Black (or as he prefers to be called, “Father”), Caroline and her young companions — David, Margaret, Michael and Richard, Jacob, Felicia, Jennifer, Lisa, Peter, Alicia, and Rachel — are taken on as apprentices. Father’s methods are brutal but effective. Each child is forced to master one of Father’s twelve catalogues of skills. As wielders of the uncanny, they are outmatched only by the omnicompetent Father himself.
Now Father has vanished. And someone has cast a magical barrier around the dimensional intrusion that is the library; none of the twelve can cross the barrier. They are marooned outside the library.
Someone who was not one of the targeted twelve might be able to simply ignore the barrier.