"Periodical" tells the unexpected story of the human body by exploring the marvel and mystery of the menstrual cycle, from the first period to the last. From soccer star Megan Rapinoe who reveals how the Women's World Cup winning U.S. Soccer team tracks their cycles, to scientists who are discovering the power and possibilities of stem cells found in period blood, to young activists flipping the bill on period tax one state at a time, and celebrities like Gloria Steinem, Naomi Watts, and Anna Konkle advocating in their own rights, we uncover the the shocking truths, challenge taboos, and reveal some hacks and celebrate the untapped potential of this special nutrient-dense blood.