Who will be Iran’s next leader?

When Ayatollah Ruhollah Khomeini, the charismatic leader of Iran’s Islamic revolution, died in 1989, hundreds of thousands of mourners packed the streets, fearful of what might happen next. Nowadays the mood is very different. For more than six months Iranians have been demonstrating en masse, chanting death to Ayatollah Ali Khamenei, the founder’s ailing successor as supreme leader. Yet no one knows who might fill his shoes when he goes—or whether the Middle East’s last theocracy will actually survive.