Christopher finds wellington-mrs shears' dog-dead. a policeman arrives at the scene and tries to touch christopher so christopher hits him. he goes to the police station and gets a caution.
Christopher decides to try and find out who killed Wellington even though his father told him not to. he chats with Mrs Alexander for a bit
he meets mrs alexander at the park and she explains that christophers mother had an affair with mr shears.
christopher finds letters from his mother which are dated 18 months after she 'died'. christophers dad explains that his mother is still alive in london and that he killed wellington because he had an argument with mrs shears
Christopher decides to go and live with his mother because he is afraid that his father will kill him because he killed wellington. he gets the train to london and a policeman tries to take him back but christopher hides and eventually makes it to london
he meets his mother who is living with mr shears but mr shears wants him to go back but his mother says he can stay as long as he needs. then, christopher and his mother drive back to swindon so christopher can do his a-levels