This new eight-part series follows the life-saving work of the medics of the largest mobile children's critical care service in the UK. The Children's Acute Transport Service, CATS, has highly specialised emergency teams who make sure that any seriously ill child who needs intensive care gets it, where ever they are. CATS make a 100-mile blue light dash so a newborn baby boy can have emergency heart surgery; a little girl with suspected meningitis is rushed from her local hospital in Southend to St Mary's in Paddington for intensive care; and an eleven year old boy in Romford is having mystery fits and needs specialist care to keep him alive while they try to discover what is causing his illness.