Mary escapes from Loch Leven Castle with the help of George Douglas and raises an army. However, she is defeated at the Battle of Langside and flees to England, seeking the protection of her cousin, Queen Elizabeth I.

Instead of providing refuge, Elizabeth I imprisons Mary. Elizabeth fears Mary's claim to the English throne and the threat she poses as a Catholic figurehead. Mary is moved between various castles and manor houses in England, always under guard.

The Northern Rebellion, a Catholic uprising in England, aims to depose Elizabeth and place Mary on the English throne. The rebellion is crushed, but it reinforces Elizabeth's suspicions of Mary.

Pope Pius V issues the papal bull "Regnans in Excelsis", excommunicating Elizabeth I and declaring her deposed. This emboldens Catholic plots against Elizabeth and further implicates Mary.

The Babington Plot, a plan to assassinate Elizabeth and put Mary on the throne, is uncovered. Mary's letters, which appeared to endorse the plot, are intercepted and used as evidence against her.

Mary is put on trial at Fotheringhay Castle for treason. She argues that as a foreign queen, she is not subject to English law, but she is found guilty.

After much deliberation and political pressure, Elizabeth I signs Mary's death warrant, though she delays its execution.

Mary, Queen of Scots, is executed by beheading at Fotheringhay Castle. Her execution marks the end of a long period of political and religious turmoil.