Aging looks like biology's oldest unsolved problem, and this film follows the scientists trying to treat it as a disease rather than a fact of life. A Harvard professor self-experiments with compounds he believes slow his own cellular clock, while researchers study a five-year-old boy whose rare genetic condition ages his body decades ahead of schedule, hunting for what his cells reveal about the aging process in everyone else. The film also visits a 95-year-old woman who smokes two packs of cigarettes a day and shows no sign of slowing down, a living contradiction to any tidy theory of decline. Between these cases it lays out competing scientific explanations for why bodies age at all, and the more mundane interventions under study, including claims that blueberries can delay some signs of aging. The film closes on the harder question underneath the research: if scientists do learn to push the human lifespan past 120 years, what that would do to a society built around dying on schedule.