Of course, that wasn't the only tension in their relationship. Mary, a Catholic, had long eyed the throne in England, knowing she'd have the support of English Catholics. Ultimately, she abdicated the throne in Scotland (it belonged, then, to her son, a literal baby), and went to England to find refuge with Elizabeth. Spoiler: That didn't go so well for her. Elizabeth imprisoned her cousin and, eventually, had her executed after uncovering an assassination plot that Mary (probably) knew about.