Fierce Creatures — A.W. Hartoin

Another day. Another disaster. After surviving a kidnapping and battling with spriggans, Matilda Whipplethorn finds her life in a suburban human house pretty boring. She's been excluded from school because of her fire-making abilities and her former friends are afraid of her. Salvation comes in the form of a life-threatening illness. Her tutor, Miss Penrose, needs a medication and there's only one place to get it, the spriggans. Matilda heads back to the antique mall to save Miss Penrose even though it just might cost her everything.