The Left Hand of Darkness is a science fiction novel written by Ursula K. Le Guin. It is set in a future where humans have colonized other planets and follows a diplomat named Genly Ai on his mission to a planet called Gethen. The inhabitants of Gethen are androgynous and only become male or female during a period of sexual receptivity. The Left Hand of Darkness explores themes of gender, sexuality, and the complexities of cultural differences.