After rereading a version of I Know an Old Lady Who Swallowed a Fly, Joan Holub wondered what ever happened to that fly. She found out -- and wrote this funny and accurate story about digestion. Using a combination of rhyming fiction and scientific facts, the story follows the fly's path through a young boy's digestive system.

The detailed scientific information shows how the digestive system works from beginning to end. Patrick Girouard's bright cartoons comically depict the fate of the unfortunate fly. Some interesting facts about food and digestion are included at the end of the book along with a diagram of the entire digestive system.