Reign: Season 3, Episode 7

3 - 7: The Hound and the Hare

When Prince Don Carlos of Spain visits France, Mary uncovers a dark secret he is hiding and enlists in Catherine to advise her on how to handle. When Gideon, the new ambassador from English court arrives, suspicions arise about what his true intentions are, while Bash's pursuit of the mysterious killer comes to a head at Greer's tavern.