The Wayward children series

Cora Miller, a student at Eleanor West's Home for Wayward Children, is tired of her adventures, and asks to be transferred to the Whitethorn Institute, which promotes conformity and tells students to ignore the doors that appear before them. Soon, the oppressive atmosphere of Whitethorn crushes Cora, and she decides to leave. But Whitethorn doesn't allow her or anyone else that privilege, trapping the students there for his own purposes.

". . . tells the origin story of Lundy, a very serious young girl who would rather study and dream than become a respectable housewife and live up to the expectations of the world around her. As well she should. When she finds a doorway to a world founded on logic and reason, riddles and lies, she thinks she's found her paradise. Alas, everything costs at the goblin market, and when her time there is drawing to a close, she makes the kind of bargain that never plays out well. For anyone . . ."--Provided by publisher.

When Jack left Eleanor West's School for Wayward Children she was carrying the body of her deliciously deranged sister--whom she had recently murdered in a fit of righteous justice--back to their home on the Moors. But death in their adopted world isn't always as permanent as it is here, and when Jack is herself carried back into the school, it becomes clear that something has happened to her. Something terrible. Something of which only the maddest of scientists could conceive. Something only her friends are equipped to help her overcome. Eleanor West's 'No Quests' rule is about to be broken. Again.