Deryn Blackwell is a walking, talking miracle. At the age of 10, he was diagnosed with Leukaemia. Then 18 months later he developed another rare form of cancer called Langerhan's cell syndrome. Only five other people in the world have it, he is the youngest of them all and the only person in the world known to be fighting it alongside another cancer, making him one in seven billion. This is the true story of the extraordinary lengths that a mother went to, to help her dying son.