S6·E12 Inheritance

Briefed to protect Grand Duke Nicholas, the heir to the throne of a small European state who has had kidnap threats made against him, the team hide him at St. Heart's, where the arrogant prince must learn to behave as a commoner with hilarious consequences. During this episode, Zoe is still shaken by the fact that she may be the daughter of The Mastermind. She uses her DNA and finds she has a sister, B:9:2:K:L:O:E:7 (Kloe) who is later revealed to have tampered genes. She's dangerous, and can't become an M.I.9 agent. Kidnapping the heir and demanding 10 million pounds, Zoe must stop her sister, alone. After the mission is over, Frank tracks Zoe's DNA all around the world, and sees that there are many matches. Too many.