This programme tells the amazing story of the longest recorded underground survival in history. After nearly a year and a half underground, the cave dwellers emerged in tattered clothes, blinded by a sun that some of the children had forgotten existed. This programme follows four of those young heroes, now in their 70s and 80s, as they travel back to the Ukraine with their grandchildren to re-enter the cave for the first time in more than 60 years. In what is now known as Priest's Grotto, the families created a refuge in a dangerously hostile environment. They were led by family matriarch Esther Stermer, whose fierce resolve kept the underground community intact. The teenage boys and the young men of the underground community put their lives on the line every time they had to venture out to gather firewood and collect food and essential supplies. What they accomplished was remarkable. Every single person, from grandparents to a one-year-old baby, emerged alive. This remarkable story is told using a combination of archive footage and a dramatic re-creation of what life was like for the subterranean survivors. It is an amazing story of triumph in the face of the most unbelievable odds.