It is six days before Christopher can go in his father's shirt box again. On the fifth day it rains very hard and Christopher watches the water falling out of his window.
On the sixth day Christopher's father is called out on an emergency - there has been a flood - so Christopher goes to the shirt box.
There are 43 letters in total - all addressed to Christopher.
In one letter his mother writes about happy times when they bought Christopher a train set and he loved it. In the second letter his mother explains in some detail why she left him. She says she was hot tempered and not as good as his father at looking after him. She fell in love with Eileen's Roger because she was lonely and he was lonely, and when he asked her to move to London with him she agreed, because she thought it would be better for everyone. In the third she writes that she hopes he got the present she sent.
After the forth letter Christopher feels giddy and sick that his father lied to him that his mother was dead. He lies in bed curled up. Christopher doesn't remember much after that - just waking up after dark with vomit on his bed.
His father walks in, realizes what's happened and apologizes and apologizes. Christopher is quiet and feels him touching his shoulder but he doesn't mind. When he lifts Christopher on to the bed to take his clothes off and put him in the bath, he doesn't mind either.
Christopher compares how the mind works and how computers work
After Christopher's father gives him a bath, he is very open with Christopher and says that he can trust him and that he is sorry. He says that he was only lying to protect him, but that from now on he would always be honest. He tells Christopher that he was the one who killed Wellington. He and Eileen had been getting on really well after his mother left and he thought that one day they might all move in together, but he and Eileen had fights. After one really horrible one where she said horrible things, she threw him out and the dog came after him, and that's when all the bad feelings over the last two years came bubbling up.
Christopher is scared when he hears this and waits for his father to fall asleep in the living room. He takes his Swiss army knife and Toby, puts on his coat, and goes out of the house. He squeezes between the wall of the shed and the fence and thinks what to do next.
From his hiding place, Christopher watches the stars and notes the different constellations.
This section is the turning point of the novel. It is through reading that Christopher uncovers the biggest secret of all: Haddon really celebrates the power of communication through the written word. In the way that Christopher has enlightened us about how he sees the world by writing his story, his mother’s letters shed light on the mystery that has been puzzling him. Note that Christopher's spelling is great but his mum's isn't!
The original mystery of Wellington actually pointed to a fundamental mystery about Christopher's own life - what began as trivial became profound. Structurally, this novel is not too distant from classical tragedy. Think of Oedipus, who, searching out the riddle of the Sphinx, instead learns a fundamental secret about his own life that had previously been hidden from him. Classical tragedy also brings the fall of the house, and here too the revelation destroys a home - Christopher no longer feels like his father's house is his home, and he begins his long journey to find his mother.
Christopher is jolted out of his pattern of reacting violently to touch, because of the extraordinary discovery he has made. A non-autistic child might have responded with uncharacteristic calmness when faced with such a shock, and here Christopher responds with uncharacteristic passivity. There is a very telling quote in chapter 167 where, apologizing and explaining to him, Christopher’s father says: ‘Life is difficult, you know. It’s bloody hard telling the truth all the time.’ In actual fact, Christopher finds the difficulty of life to be the exact opposite – he seems to find it impossible to lie. In chapter 167 Christopher compares his mind to a computer and when his father apologizes and he says nothing, it is almost as though his whole being is re-booting in order to process this shocking information.
As far as Christopher is concerned his father is a murderer, and he must escape. The image of Christopher’s father killing the dog is made to sound almost cartoon-like and totally removed; yet killing a dog with a garden fork is extremely gruesome and brutal. Christopher’s fear after finding out about Wellington is totally understandable - it is as though his father has been revealed as a stranger. If his father has killed Wellington and lied about his mother, then Christopher cannot trust him at all.