It's the first day of fourth-grade for twins Andy and Anna. Andy is a shy boy obsessed with dinosaurs and Anna is an adventurous girl willing to take risks. One day when they step off the school bus, Anna suggests taking a shortcut through a dark alley to get home. As they navigate through the abandoned alley, they find a mysterious large egg tucked under a bush. They take it home and try to hatch it, careful not to tell their parents who...