The extraordinary story of Katie and Eilish, 3-year-old Siamese twins from Ireland. Parents Liam and Mary Holton are faced with the hardest decision of their lives: should the twins be separated in a high risk operation? If they go ahead it will be the most difficult operation of its kind ever undertaken. It´s a decision that has cast a shadow over the twins, since they were born. Doctors in Dublin decided not to operate because the risks were considered too great. They thought the chances of a successful separation would be higher once the twins were older. But with Katie and Eilish happy and apparently accepted in their community the decision was agonizing. In the end Liam and Mary Holton decided to go ahead. And on April 1st 1992 surgeons at Great Ormond Street Hospital in London operated. Four days later, Katie died of heart failure. A post mortem showed that she had a weak heart. Eilish survived. The film records 12 crucial months in the lives of the twins and their parents. Liam and Mary Holton talk frankly about their hopes for Katie and Eilish, and their frustrations. They explain why they decided to go ahead with surgery, despite the huge risks. They talk also about the loss of Katie, and their conviction, nevertheless, that the decision they took was the right one. The result is a restrained, but intensely moving portrait of an exceptional family.