The story follows two young children, Tommy and Lucy, as they embark on an adventure through the natural world. They meet Madam How, who teaches them about the science of how things work, and Lady Why, who teaches them about the reasons behind the things they see. Together, they learn about the wonders of the world and the importance of understanding and respecting the natural environment. Through their journey, the children gain a deeper appreciation for the beauty and complexity of the world around them and the interconnectedness of all living things. Overall, the book is a delightful and enlightening tale that encourages young readers to explore and understand the natural world.