The Left Hand of Darkness, written by Ursula K. Le Guin, is a groundbreaking science fiction novel that takes place on the planet Gethen, where the inhabitants are neither male nor female for most of the time. The story follows a human envoy named Genly Ai as he navigates the complex social and political landscape of Gethen, challenging his own assumptions about gender and identity. Le Guin's exploration of gender and society makes this book a must-read for any science fiction fan.