It's Matthew's birthday and the family have gone to London. They go on an open-top bus and visit the planetarium. Matthew explains that he wants to be an astronaut when he grows up. It is discovered that Matthew has been adopted. In Maths the following morning, a blue-white light appears and enters the classroom. It seems to be searching for someone. It lands on Matthew and Matthew immediately finds that he can solve the problems straight away, when he couldn't before. Matthew's parents notice his unusual behaviour as he starts to ask some unusual questions. Matthew has a fever and starts talking aloud. His parents discover Chocky, who seems to be an imaginary friend.