Betty and Sam, nine-year-old friends, are given a project by their grumpy teacher, Miss Broadchalk: WHAT MAKES US HUMAN BEINGS? They begin to grapple with the challenge by observing nature all around them and conclude that animals do everything better than we humans. Downhearted, they seek help from Betty's uncle, Professor Humphrey Tanglewire, a retired inventor. His enthusiasm cheers them up, and he gives them the key word - "HANDS" - and 12 questions to answer. Betty and Sam then enter upon a journey of exploration of the structure and function of the human hand as compared with animal limbs, and the connection between the large human brain and the many activities of the human hand - hands at work, hands that create, hands that "talk," hands that "see," hands that make music, hands in sports, hands that love, and finally how each human hand is different and how each one of us can be identified by his or her fingerprints. All in all, the children decide that "YOUR HANDS ARE YOU!" Grumpy "Chalky" becomes a joyous, smiling teacher after she goes over Betty and Sam's project folder. She gives them top marks. For the rest of the morning, all classes are cancelled, to the delight of the whole class, in order to make time for Betty and Sam to present their work. The children become the heroes of the day.