This documentary begins with a family secret. In his epic BBC TV series, The Ascent of Man, Jacob Bronowski presented a triumphalist history of civilisation, in which he gave the credit for mankind's progress to science. Science, he seemed to proclaim, was unequivocally a force for good in the world. But what nobody, not even his own daughter, knew was that during the Second World War, he used his mathematical brilliance to improve the murderous efficiency of aerial bombardment - he used science to kill people.
Bronowski died almost forty years ago. His daughter, Lisa Jardine, grew-up believing she was his case-study of what he wanted for the whole next generation. Now she's both an historian of science and public figure as Chair of the Human Fertilisation and Embryology Authority.
This film follows Lisa as she stumbles upon her father's secret in a locked cupboard at her parents home in California. Here she finds the top-secret research papers that Dr Bronowski produced for the wartime British government. As a mathematician he calculated the most effective way to destroy enemy cities, to smash railways networks and start firestorms.
Following a trail from California, to the East End of London, where Bronowski grew-up, to the English countryside where Lisa grew-up with him, Lisa turns detective on her father. She discovers that, in 1945, he was among the first British scientists to visit Japan in the aftermath of the Atomic Bomb, and how this experience coloured the rest of his life. She unpicks his broadcasting career and her own extraordinary childhood under the unflinching gaze of this powerful mind.
Lisa is aware there is no moral equivalence between the Allied bombing campaign and the atrocities of the Holocaust. But she must find out how her father emerged from the shadow of World War Two with his optimism for science and for the future intact.
Lisa finds her answer where she least expects. But is it what she has been searching for? She is surprised to find she has a completely new understanding of her father, which allows him to become a role model for her more than ever before.