The video clip shows a healthy, happy child smiling from ear to ear, her milk teeth gnawing at a pink fluffy toy. Within months all of South Korea would know her name: Jeong-in. It has taken the death of a 16-month-old, allegedly at the hands of her adoptive parents, to jolt South Korea’s government into what campaigners say is long-overdue action to protect the most vulnerable children, amid a dramatic rise in reported abuse cases over the past...