รายละเอียด(อย่างย่อ) Everyone knows that little sisters can be an-noy-ing! So when Ravi gets annoyed with Ruby and breaks her toy car in a rage, everyone goes to bed upset. Ravi wakes up the next morning with a bright red grumpy hat stuck fast on his head! And he can’t get rid of it, no matter how hard he tries... Ravi learns how to swap his grumpy hat for happy socks in this uplifting story about siblings, family life and controlling bad moods.