My heart is my own: the life of Mary Queen of Scots. John Guy. 2004.

She was crowned Queen of Scotland at nine months of age, and Queen of France at sixteen years; at eighteen she ascended the throne that was her birthright and began ruling one of the most fractious courts in Europe. She rode out at the head of an army in both victory and defeat; saw her second husband assassinated, and married his murderer. At twenty-five she entered captivity at the hands of her rival Queen, from which only death would release her.