Jason's sisters get all the attention-and cause him all sorts of trouble. His older sister, Tayleigh, once made a wish that got her suspended from the dance team, and then Jason had to move to a new middle school. His twin, Polly, also made a wish which almost ruined the family vacation when she started hearing and seeing Thomas Jefferson's ghost everywhere. Jason can't wait to get away for a bit, and lucky for him, he gets to go on a band trip to the happiest place on earth
Along with his big brother, Bryant, and his best friend, Scooter, Jason is headed to a special theme park in Florida. Away from his family, Jason will be free of drama and the strange magic that surrounds his sisters. But then he makes a mistake of his own: he wishes for the truly magical experience. Miraculously, he is given the Key to the Kingdom, and he befriends a young woman whose family helped develop the theme park.
Jason soon begins to realize that things are coming much too easily, and the wish comes back to haunt him. In a family filled with fulfilled fantasies, did he really think he would be any different? Jason remembers what his big sister said after her wish: "Be careful what you wish for." He and his friends must now figure out how to solve a mystery and make it safely home no worse for wear