The main character is a young man who belongs to the second group and decides to go to the underground world to find his missing sister. The plot of the book "Мы одной крови ты и я" by [Author's name] is a gripping and thought-provoking tale that delves into the theme of technology evolution and its impact on human society. Set in a post-apocalyptic world where a global catastrophe has left only two groups of survivors - those who live underground and those who fight against nature and each other on the surface - the story follows the journey of a young man named [Protagonist's name]. As the protagonist sets out to find his missing sister, he discovers that the underground world is not just a refuge from the harsh conditions on the surface, but also a technological marvel that has allowed its inhabitants to thrive despite the devastation. The author masterfully weaves together action, adventure, and philosophical musings on the nature of technology and its role in shaping our future. The story begins with the protagonist living on the surface, struggling to survive in a world ravaged by natural disasters and constant warfare. He soon learns that his sister, who was part of the underground community, has gone missing, and embarks on a dangerous journey to find her.

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