Filmed over the course of a year, Great Ormond Street features unprecedented access to doctors from one of the top children's hospitals in the world as they make some of the hardest choices in medicine. When medical technology seems to offer so much, every parent with a sick child will hope that something can be done, but doctors must decide when enough is enough. For the first time on television, cameras follow Great Ormond Street Hospital's doctors into the meetings where they come face to face with the most difficult ethical dilemmas on a daily basis. Pushing the Boundaries focuses on the work of the largest children's cardiac unit in the UK. Two of its surgeons, Martin Elliott and Victor Tsang, perform extremely advanced surgery that isn't carried out anywhere else in the country, and the team's success rate for heart transplant is well above the international average. Consultant cardiologist Phil Rees is the team's longest serving doctor, and admits that he still finds it difficult not to become too emotionally involved in individual cases The film documents the stories of four children as the team attempts to save their lives: the parents of 8-month-old Aicha, given only a few months to live, refuse to accept the team's decision that there's nothing else to be done, forcing the doctors to reconsider their decision; 8-month-old Natalie's parents are offered surgery that might save their daughter's life, but the procedure is very complex and has never been tried before; 9-year-old Bryan has already had several life-saving heart operations but now a high-risk heart transplant is all that's left to him; and Blessing's parents must decide whether to agree to a perilous operation on their daughter when she is only two days old. Through these stories the film explores when it's right to treat a child. As surgeon Martin Elliott says: 'Just because we can, doesn't mean we should.'.