The human brain sits inside the skull as roughly three pounds of tissue, and this film works through what that tissue actually does, lobe by lobe. The frontal lobe handles planning and self-control, the temporal and parietal lobes handle language and spatial sense, and the occipital lobe processes vision, with the visual cortex taking up a larger share of human brain tissue than it does in most other species. The film compares brain-to-body ratios across animals, noting that the human quotient runs nearly twice that of a bottlenose dolphin and three times that of a chimpanzee, and it covers the left-right split in function, with language processing concentrated in the left hemisphere for most people. It also surveys what goes wrong: stroke, closed head injuries, Parkinson's and Alzheimer's disease, multiple sclerosis, and tumors, each explained by which part of the brain's architecture fails. The result is a straightforward anatomy and function primer rather than a narrative, built around structure first and disease second.