Charlie and the mysterious Ostrich Egg is a story about a boy named Charlie who finds a giant white egg in the woods near his house. He imagines different animals that could be inside the egg, but when it hatches, a baby ostrich emerges. Charlie and the ostrich, named Ozzie, become fast friends and go on many adventures together. The story teaches that life is full of surprises, and the most unexpected moments can lead to wonderful experiences and friendships.