Who is Nadir Khan?

Nadir Kahn is an anti-British poet who dates Saleem's aunt Emerald and then, while hidden from British troops under the Aziz house, falls in love with her sister Mumtaz and marries her. Their marriage is a secret, since he cannot come out from hiding in the basement of the Aziz house. Emerald, whom he dated first, betrays his hiding place to the police, forcing him to run away, and Mumtaz is left still a virgin after two years of marriage. Kahn shows up later in the story, meeting Amina Sinai (the name that Mumtaz has been going by) at the Pioneer Café, but Saleem lets his mother know that she is being watched, and she breaks off their relationship.