“Fablehaven: Grip of the Shadow Plague,” the third installment in Brandon Mull’s excellent kid-lit fantasy series, is as delightful as the first two, full of the subtle wit and great storytelling that have made these books my favorite post-Harry-Potter magical series. Our heroes, 14-year-old Kendra and her little brother Seth, spend summers at their grandparents’ estate, which turns out to be a preserve for magical creatures. In “Grip of the Shadow Plague,” there is concern that the head of their good organization might be a traitor to the bad side; meanwhile, a mysterious darkness is overcoming Fablehaven. Mull’s style is to write fantasy for non-fantasy audiences, with kids who act like real modern-day kids. He continues to introduce new facets to the mythology (Kendra’s fairy powers, some Native American-inspired supernaturalism), and he sets up elements that will surely come into play in later books. (Two words: zombies. ZOMBIES!) The book comes out next week, but you can pre-order it now. If you haven’t picked up the series yet, do it! My brief reviews of the first two books are here and here.