The scene opens up on a woman, Cheryl visiting an astrologer to see her future in the stars. The man is a con artist, deceiving his customers to get money out of them, to which he finally admits this to the woman who has been visiting him frequently, and is using her mortgage money to pay. He walks to the window where a shooting star is heading exactly for his house, and he is possessed by an unknown being in front of the woman, and proceeds to possess her. Later, Luke, Clyde and Rani are visiting an exhibition with the astrologer, Martin Trueman, as the event is free. Rani's Parents and Sarah Jane also show up and each person fills in a card with their birthday and star signs on it and hand it to Cheryl who is now working with the astrologer. Luke is slightly upset given that he does not have a star sign as he was never born, but activated.
The show starts and Trueman begins to ask random dates and three people including Clyde stand up, as this is their birthday, although Clyde is unsure why he stood up. Sarah Jane tells him its a trick of persuasion and she is sceptical about the entire show. Next he asks for a person and begins to tell truths about her life, as the woman herself is shocked but enjoying the show. Sarah Jane then tells Luke, Clyde and Rani that the woman was a plant and that Martin Trueman already knew her. Next Martin calls on Rani, and starts detailing that she has recently moved house and gives few details about her family. Rani is slightly amazed but not suspicious. Next he calls on Sarah Jane Smith, and begins detailing her travels with the Doctor in front of the audience, no-one but Sarah Jane, Luke and Clyde (and possibly Rani) could know of these stories and Sarah Jane is instantly suspicious. Martin Trueman then predicts her downfall.
Clyde threatens Sarah but they manage to talk him out of it, which leads Sarah Jane to believe that Trueman's control on people can be repressed by persuading them to do something that they do not normally want to do. Meanwhile, using in his broadcast to the world, Martin Trueman takes over each star sign one by one, starting with Gemini - including Rani's mother. The world is in confusion as people are accepting the 'Ancient Lights'. Sarah Jane and the gang head to the New Theatre in East Acton to stop the broadcast, but the possessed Children of Gemini threaten to stop them. Clyde bluffs his way through by making up horoscopes.
The Ancient Lights create a portal through to the theatre. Martin reveals that Luke's theory on the Ancient Lights is true. Martin insinuates that in the old universe, they used to control all lifeforms. The Ancient Lights survived the Big Bang and needed Martin Trueman to rule the world because, he was the 'Chosen One'. Sarah Jane tries to talk him out of it but to no avail. Rani and Luke try to shut down the broadcast by flicking the mains switch off, but it is protected by the Ancient Lights' energy. Rani is an Aries and eventually becomes possessed, leaving only people with the star-sign of Taurus, which includes Sarah Jane, not under Trueman's control. However Luke, who was not born and so does not have a star-sign, realises he can stop the power of the Ancient Lights by breaking Trueman's circle. Realising that he has been beaten, Trueman cannot bear to return to his former life and instead chooses to become one with the stars, disappearing in a trail of golden dust. In the aftermath, the unaware Earth authorities begin a search for Trueman, and Sarah Jane declares the date will be Luke's equivalent to a birthday.