The Master's finally done it. He's won. He summons his other selves to a celebration of his ultimate victory. And they come - from across time and dimensions.?But he's forgotten to invite someone. And Missy's not happy. Has the Master really conquered the universe? Or has something more awful been unleashed? Something that even all the Masters cannot stop? Missy is determined to reveal the truth. Because one fact about the Master's existence never changes. No-one can trust the Master. Not even the Master.