In early 2016, the United States secured the release of some of its citizens imprisoned in Iran. Months later, Nazanin Zaghari-Ratcliffe was taken hostage, caught up in the backdraft of the US deal. Her fate and the decades-old issue of an unpaid debt finally collide.

Presenter: Ceri Thomas
Producer: Matt Russell
Original music: Tom Kinsella
A Tortoise Media production for BBC Radio 4