For 10 points, identify this queen of Scotland who was executed for treason by her cousin, Elizabeth I of England.
This monarch allegedly wrote a series of letters and love poems to the Earl of Bothwell, known as the Casket Letters, which implicated her in the murder of her husband, Lord Darnley. Sir Francis Walsingham implicated this queen in a plot to help Spain invade England and place her on the throne. Although this monarch would never become queen of England, her son, James I, would eventually become king after this queen's execution. For 10 points, identify this queen of Scotland who was executed for treason by her cousin, Elizabeth I of England.
This monarch allegedly wrote a series of letters and love poems to the Earl of Bothwell, known as the Casket Letters, which implicated her in the murder of her husband, Lord Darnley.
{Mary, Queen of Scots} [accept {Mary I} of {Scotland} or {Mary Stuart}, prompt on partial answers]