A monthly series in which broadcaster and acclaimed historical novelist Sarah Dunant delves into the past to help frame the present, bringing to life worlds that span the centuries.

Taking modern day anxieties as its starting point, the programme considers how certain questions are constant, yet also change their shape over time.

This month, Sarah takes us to the brink - to moments where leaders are willing to cross the ultimate line. She'll be asking what happens when the enemy you're negotiating with has nothing to lose, and questioning whether the threat of apocalypse can be good for the soul.

From Caesar crossing the Rubicon in ancient Rome, to medieval apocalyptic fears, via a radical preacher with rhetoric so powerful that it catapulted him onto the global stage, these are moments of fire and fury when the end seemed nigh.

Guests include Dr Hannah Cornwell from the University of Birmingham, Dr Stefano Dall'Aglio of the University of Edinburgh, and Dr James Palmer from the University of St Andrews.

Presenter: Sarah Dunant