In the story "Horton Hatches the Egg," Horton the elephant discovers a bird named Mayzie who is too lazy to care for her egg. She convinces Horton to sit on the egg while she takes a vacation. Despite the challenges and ridicule from other animals, Horton remains committed to his promise. As time passes, Horton faces harsh weather and mockery, but he stays loyal. Eventually, the egg hatches, revealing a unique creature that surprises everyone. The story emphasizes themes of responsibility, loyalty, and the importance of keeping promises, showcasing Dr. Seuss's signature whimsical style.