Philip Ball tells the story of Alexis Carrel, the French surgeon who worked to preserve life outside the body and create an immortal chicken heart in a dish. His quest was to renew ageing flesh, repair and rebuild our bodies and keep them healthy far beyond the usual human lifespan. In the early twentieth century his science was pioneering but his mission to achieve eternal life was underpinned by a dark and terrifying agenda. Carrel was a racist who advocated eugenics to preserve the superior civilisation of the West. Philip Ball discusses the history and cultural impact of the tissue culture techniques developed by Carrel with social historian Professor Hannah Landecker of the University of California at Los Angeles. And he finds out about the legacy of Carrel's research from Dr Madeline Lancaster of Cambridge University, one of the pioneers of the growth of brain organoids from stem cells; small clusters of neurons and other cells, rather like mini organs no bigger than a dried pea.

Philip Ball's story is of Ibn al-Haytham, the first scientist, and his book of optics that defined how we see.

Naomi Alderman's Science Story reveals how Lady Mary Wortley Montagu experimented on her own child in a quest to prove that smallpox inoculation works. Born in 1689 in a position of some power and influence, Lady Mary travelled to Constantinople as the wife of the ambassador to Turkey and witnessed 'variolation parties'. Here 'a nut shell' of virus on a needle is put in an opened vein to infer immunity. Having lost her own brother to smallpox and survived with terrible scaring herself, Lady Mary knew first hand the dangers of the deadly disease. She became the first person to bring smallpox inoculation to the West. Medical historian Lindsey Fiztharris tells the remarkable story of how condemned prisoners are given the opportunity to escape execution under the orders of King George I if they are given the virus and survive. Tim Spector, Professor of Genetic Epidemiology at Kings College, London, and Naomi discuss some of today's counter intuitive treatments, such as faecal transplants.

Philip Ball reveals the tale of a small booklet 'On The Six-Cornered Snowflake", written by Johannes Kepler as a New Year's gift. The C17th astronomer wished to explain the intricate and symmetrical shape of winter's tiny stars of snow. His insightful speculations about minerals and geometry was the beginning of the modern understanding of crystals.

Naomi Alderman's tale is of Lucretius, author of a 2000 year old poem that theorised about atoms and the natural world. Written in the first century BCE, during a chaotic and frightening time when the Roman Republic was collapsing, Lucretius encouraged people to feel free through contemplating the physics of the Universe. Naomi learns that many of the theories still hold water today and that the poem, De Rerum Natura, is an epic beautiful and persuasive piece of work.