Third programme in the series following the life-saving work of the medics of a mobile intensive care service for children. The highly specialised emergency teams from The Children's Acute Transport Service, CATS, make sure critically ill children who need intensive care get it, wherever they are. The team race to save a 10-year-old girl who needs to be moved to Great Ormond Street Hospital for a heart transplant, but she's already on a heart lung machine, making it that much more difficult; all of the team's skills are needed when a baby's heart stops beating; and a little girl has been knocked unconscious by a car and may have brain damage.