The Doctor and Mrs Wibbsey are catapulted from present day Earth to a futuristic civilisation in a distant galaxy. At the Robotov Palace they find the Tsar and Tsarina ruling over their empire whilst human workers toil on satellite moons. The Doctor is mistaken for an old ally of the Tsarina's, but then suspected of treason when the Palace comes under attack. Dark secrets are lurking in the shadows, and the mysterious Father Gregory will set off a chain of events which have long-lasting consequences for the Doctor and Mrs Wibbsey.