Central Asia was the birthplace of yoghurt, as Golden Crescent nomadic tribes domesticated sheep and goats and began to curdle milk. Aylin Bozyap grew up in Istanbul, and as a child used to take the ferry with her family to the port town of Kanlica to eat yoghurt. Recreating the journey, she takes as her guide the political scientist, food historian and author Professor Artun Unsal, who finds the yoghurt a poor immitation of its former self. In search of something better they visit the artisan yoghurt maker Mehmet Nazli, whose family has been making yoghurt for many years, and who still makes it the traditional way. His son and grandson also work in the business, but the work is hard and they don't make much money, with the profits staying mainly with the middlemen and shops. On the other side of Istanbul they visit an artisan yoghurt maker who has had to stop producing; the quality of the milk is no longer good enough, nor the city clean enough, to make real yoghurt any more. Finally they go to the Silivri Yoghurt Festival, an annual celebration of traditional yogurt, and meet one of the winners. They also meet the deputy mayor of Silivri, who takes them to visit a disused yoghurt house that Professor Unsal is keen to see turned into a yoghurt museum. In the studio Sheila Dillon and Aylin taste a range of plain yoghurts, as well as a typical British style yoghurt.