What a curious title!
The title, The Curious Incident of the Dog in the Night-Time, comes from a line in the Sherlock Holmes story “The Adventure of Silver Blaze.” In this story, Sherlock Holmes and Watson investigate the disappearance of a horse, Silver Blaze, and the apparent murder of his trainer. Part of the final deduction hinges on the “curious incident of the dog in the night-time” that did not bark at all when the horse was stolen— so it must have been taken by someone familiar to the dog so it would not arouse suspicion. In the book version of Curious Incident, Christopher references this story by name. In both the book and the play, he mentions his love of Sherlock Holmes. Both Holmes and Christopher are experts at noticing the smaller things in life that others may miss or ignore and both are committed to solving crimes even against the wishes of others. The use of the Curious Incident title may even refer to the actual crime of killing Wellington: not only was the dog killed in the nighttime as in the original Holmes but he was in fact killed by someone known to him, making the allusion even more pertinent.