Strings — G. Miki Hayden

Robert, an ordinary boy, finds himself in a newly chaotic world. Buildings move when and where they please, and time jumps around according to no known laws of physics. For Robert, getting to his regular school in the morning is next to impossible. As for getting home... But then, Holden - a boy he and his friend, Nila, meet in a cave - offers them a string. No, not twine, but a string of the kind that forms the universe. Teeny and tiny, and invisible to the naked eye, this string will take Robert and Mila to their homes and way, way beyond... Accompanied by a memorable cast of characters, Robert and his friends follow the string on a journey across time, space, and dimension to discover the answer to a mystery: Who has caused the world to fall apart?