Why were there three popes at the same time?

For almost two millennia, the Pope has been a figure of supreme spiritual authority for Catholics around the world. But in the late 14th century, Catholics found themselves with not one, not two, but three popes. Where did this plethora of popes come from? And who among them was the genuine article? Joëlle Rollo-Koster shares the origins of this papal predicament. [Directed by Kaspar Jancis, narrated by Adrian Dannatt, music by Kaspar Jancis].