Horizon follows the emotional journey of three young people with currently untreatable conditions to see if, within their lifetime, they can be cured. Sophie Morgan is determined not to spend the rest of her life in a wheelchair. She is tempted by the online claims of unregulated private clinics promising a cure using stem cells. Anthony Bath was just 20 when his right leg was amputated after a botched pinning procedure. In Finland, Anthony witnesses one of the world's first operations in which stem cells are used to replace bone. Dean Third was diagnosed with dilated cardiomyopathy, a condition in which his damaged heart could cause his death at any moment. Desperate for a cure, he visits Dr Anthony Mathur from University College London to witness the world's first trial using stem cells taken from bone marrow.