With Trident renewed for another generation, A Very British Deterrent tells the story of the remarkable events, eye-watering costs, power relationships and secret deals done half a century ago to secure Britain's very first submarine-launched nuclear missiles. In today's turbulent world, it is a story that is more relevant than ever. At the height of the Cold War, a series of political and technical crises came close to leaving Britain without a nuclear weapon of its own. In a time of unprecedented international tension and with the world locked in a terrifying nuclear arms race, one small loch in Scotland became a crucial bargaining chip to keep Britain in the nuclear game. Using the personal letters of prime ministers and presidents, eye-witness accounts and once-secret documents, this film explores how the British prime minister Harold Macmillan seized every opportunity to further Britain's nuclear ambitions, was prepared to trade a Scottish base for a new American weapon, and even jeopardised the crucial Anglo-American relationship to keep Britain an independent nuclear power.