Angie Zelter is on her way to Loch Goil in Scotland. It’s a beautiful summer’s day, and her friends have packed a picnic. But that’s not the real reason they’re there. Angie has an urgent message to deliver to the world about nuclear weapons. And she’s going to deliver it through an act of destruction.

In this episode, Matthew Syed looks at the danger that nuclear weapons pose, even if nations never use them in a deliberate act of war. He hears about the moments we came within a hair’s breadth of disaster through misunderstanding, negligence, accident and even a blackbrown bear.

It’s simple - the more weapons there are in the world, the more risk increases. But how to deal with this problem throws up complex solutions and viewpoints.

Some would like the total eradication of nuclear weapons, arguing that disarmament across the world is the only way to avoid catastrophic risk. But others worry about disrupting the delicate balance of nuclear deterrence. As Matthew hears, history shows us that scaling back the numbers is possible - even at the height of the Cold War. He asks whether the possibilities for non-proliferation and scaling back through treaties and verification could be a way forward today.

Contributors: Angie Zelter - Founder of the Trident Ploughshares movement in the UK, anti-nuclear weapons activist and Peace and Environmental Campaigner Eryn MacDonald - Global Security Analyst at the Union of Concerned Scientists Patricia Lewis - Research Director for Conflict, Science and Transformation and Director, International Security Programme Mariana Bujeryn - Global Fellow with the Wilson Center's Nuclear Proliferation International History Project and Research Fellow at the Project on Managing the Atom and International Security Project at the Harvard Kennedy School's Belfer Center

Presenter: Matthew Syed Producer: Nadia Mehdi Series Editor: Katherine Godfrey Sound Design and Mix: Rob Speight Theme tune by Ioana Selaru A Novel production for BBC Radio 4