A massive blue whale has moved into the waters near the sparkling coral reef. The gentle giant loves to float quietly and watch Rainbow Fish and his friends play in the shimmering sunlight. But because the whale is so incredibly large, the little fish become suspicious. They misinterpret his peaceful staring and assume he is planning to eat all their food. The misunderstanding grows worse when a startled fish offends the whale, making the giant creature angry and hurt. Soon, the entire reef is in an uproar, and everyone is hungry and hiding. Rainbow Fish realizes that jumping to conclusions has caused a terrible problem. He bravely swims out to talk to the whale, hoping to clear up the confusion and restore peace to their underwater home.