The pressure on Elizabeth grows as there is still no marriage and consequently no heir to the throne. Elizabeth fears that her cousin Mary Queen of Scots, recently widowed, might claim her right to the throne of England. However she is resolute in thinking that she can rule alone. Meanwhile she continues to meet Robert Dudley. When his wife dies, rumors spread that Elizabeth might be behind her death. Details of a plot to replace Elizabeth with Mary are uncovered by Walsingham. Even the Duke of Norfolk seems to be involved and is subsequently sent to the tower. (thetvdb.com)