Ed then finds Christopher's note book in which he has been recording his investigations. This makes him very angry - in the argument that follows, he hits Christopher, takes the note book from him and hides it.
Whilst looking for his notebook, Christopher discovers a number of letters sent by his mother. The letters tell her side of the story, how she fell in love with Mr Shears and how she felt she was not very good at looking after Christopher. As a result, she went to live in London with Mr Shears. Worst of all, Christopher finds out that his father stopped her from saying goodbye. This makes Christopher break down in tears.
Ed finds Christopher and explains how after his wife, Judy, left, he became close to Mrs Shears and began a romantic relationship with her. This did not work out and after a bad argument, he killed Mrs Shears' dog, Wellington. Christopher decides he cannot trust his father and goes by himself to London to live with his mother.