Home Astronomy for Children MARGARET PETERSON HADDIX INTRODUCES REMARKABLES MARGARET PETERSON HADDIX INTRODUCES REMARKABLES booksforchildren Sep 24, 2019 comments off Tweet on Twitter Share on Facebook Pinterest Playful Planets children's book series. alternate universes Book Books Children's books cyphers Fantasy Greystone Secrets HarperCollins HarperKids Margaret Peterson Haddix middle grade multiple realities multiverse mystery books for kids New York Times bestselling author plot twists Remarkables riddles Running Out of Time Shadow Children series The Strangers time travel