Over the past year, Horizon has been behind the scenes at one of Britain's leading cancer hospitals, the Royal Marsden in London. The film follows Rosemary, Phil and Ray as they undergo remarkable new treatments – from a billion pound genetically targeted drug designed to fight a type of skin cancer, to advanced robotic surgery. We witness the breakthroughs in surgery and in scientific research that are offering new hope and helping to defeat a disease that more than one in three of us will develop at some stage of our lives.