What's So Funny?

A mysterious gas is escaping from a hole in the Happy World tanker. Soon, everyone is laughing, but they don't know why. What will happen when the laughter stops? Can Grandpa find a cure for the laughing illness before it's too late?Oxford Read and Imagine is a fiction graded readers series that invites young readers into an exciting world of great stories. Follow Rosie, Ben, Grandpa and his robot Clunk on their adventures in Grandpa’s fantastic van.