In the play, as in the original book on which the play is based, the protagonist, Christopher, a teenage boy with autism, must overcome his fears of a world from which he is separated by his condition.

Such fear manifests itself in different ways. For example, Christopher finds it difficult to deal with other people, yet he knows that he must overcome his fear of interacting with them in order to get to the bottom of who killed Wellington, his neighbor's dog. Christopher sees himself as a modern-day Sherlock Holmes, and this elevated self-image makes it much easier for him to go about his detective work.

Once Christopher has finally solved the mystery of who killed the dog, another kind of fear takes hold. Having discovered that it was his father who killed the dog, Christopher immediately fears for his life.

Despite his awkwardness in the big wide world, Christopher makes the decision to head off to London to live with his mother. Sometimes it's best to run away from a source of fear instead of confronting it head-on, and this seems to be the right approach in this particular case.

In due course, however, Christopher will overcome the fear of his father and return home, where he sits his math exam, in which he achieves top marks.