Conjoined twins Marieme and Ndeye have separate hearts and lungs, but Marieme's heart is very weak and her life expectancy is poor and if she dies, her stronger sister will die with her. As the girls' health deteriorates, their father Ibrahima and staff at Great Ormond Street Hospital are forced to decide whether a separation should be considered. This programme tracks the journey of Ibrahima and the medical team as they wrestle with is a seemingly impossible decision with the help of the hospital's Clinical Ethics Committee.