The Stranger by Albert Camus?

Notice that Meursault does not have any connections and he really doesn't try to make them. The closest connection he should have is that with his mother, but she is noted to be dead and he is clearly not moved by this death. The idea of the stranger lies in this isolation. The book pushes you to see how isolated each individual really is within their own thoughts and concepts. Other people are not able to hear your thoughts or know your feelings unless you choose to share them and they choose to recognize your meaningfulness into their own thoughts and existence. Essentially, each person is a stranger to another unless connections are recognized. As for Meursault, he only knows what he does and doesn't know. If you asked him about anything outside of himself, he couldn't answer and doesn't care. This is shown through the dog and his owner. This isolation is a fundamental aspect of the human condition. We all exist in this isolation and, without our own effort and need for companionship, we will continue to be isolated, and essentially strangers amongst strangers.