The perfect next step for kids who love the Magic Tree House series, time travel, mystery, and adventure! Almost everybody who has grown up in Chicago knows about the Thorne Rooms. Housed in the deep inside the Chicago Art Institute, they are a collection of 68 exquisitely crafted miniature rooms. Each room is set in a different historic period, and every detail is perfect. Some might even say, the rooms are magic. But what if on a field trip, you discovered a key that allowed you to shrink so that you could sneak inside and explore the rooms' secrets? What if you discovered that others had done so before you? . . . And that someone had left something important behind? Eleven-year-olds Jack and Ruthie are about to find out!  "Irresistible."—The New York Times "Marianne Malone has tapped into a fantasy that is . . . completely universal."—Chicago Tribune "A solid story. Recommend this book to fans of Blue Balliett’s Chasing Vermeer."—School Library Journal