Stewart has found the mystical pencil where Alex and Sara left it, and before they can warn him, he draws a robot that comes to life--and begins to use the pencil to draw other robots.
Alex decides that the only safe place for the mystical pencil is the museum where his father works--but when Marvin borrows the pencil and begins to draw dinosaurs, things quickly get out of hand.
Sara finds the mystical pencil on the sidewalk where Alex dropped it and brings it to school on costume design day--and before Alex can explain the danger the school is full of flying pigs and barnyard animals.
