Plot summary
Simon Westbrook is arrested for causing the deaths of the French troops, based on the testimony of a prostitute who claims she saw him bragging about it. Prince Tomas shows his true colours to Queen Mary by threatening her and hitting a whipping boy when she talks back to him. After receiving a hint from Clarissa, Queen Mary, Prince Francis and Bash realize that Prince Tomas had the most to gain by warning the English. She questions the prostitute, who admits she was paid for her testimony.
Prince Francis and Bash find Prince Tomas when he's about to kill his whipping boy to cover his tracks in the plot; a fight ensues and Prince Francis kills Prince Tomas. Queen Mary, Prince Francis, and Bash return to court in time to prevent Simon's execution. Henry and Catherine, with the King of Portugal's agreement, agree to cover up Tomas's treachery - the official story is that his death was an accident. Simon leaves France as the new English envoy to Portugal. Due to her role in protecting France's ties with Portugal, Mary is able to reopen negotiations for her marriage to Prince Francis, this time pressuring King Henry and Queen Catherine for better terms for herself and Scotland.
Credits
Adapted from Wikipedia contributors, Reign season 1. HTML formatting and reference markers removed.