Y: The Last Man traverses a post-apocalyptic world in which a mysterious cataclysmic event simultaneously kills every mammal on Earth possessing a Y chromosome, except for one cisgender man and his pet monkey. The series follows the survivors in this new world as they struggle with the loss of their loved ones and the collapse of society, while attempting to restore what was lost and the opportunity to build something better. The narrative centers on Yorick Brown, the sole male survivor, and his mother, Jennifer Brown, who ascends to the presidency of the United States amidst the chaos. As various factions emerge—ranging from those seeking to maintain the old order to those embracing the new reality—Yorick must navigate a dangerous landscape while being hunted by those who view him as a biological anomaly or a key to the future of the human race.