Ms. Frizzle's class is learning about the heart. They get in the Magic School Bus because they are going to see a movie. But they find themselves on a heart-pounding adventure! The bus ends up going through Keesha's circulatory system. The class travels through the bloodstream and learns about the heart's job and how it works with the lungs. Hop on the Magic School Bus and find out what's at the heart of it all!