The tone of The Stranger is, more than anything else, apathetic. Meursault displays a unique indifference, often remarking on the interchangeability of various people, places, and things. He holds a perspective on life that is somewhat jarring for the reader to see the world through, as it is quite passive and indifferent.
This indifference sheds light on the absurd, which is predicated on the certainty of death and the seeming arbitrariness of a life without understandable meaning. It is no coincidence that this work of absurdist fiction centers around a character who is sentenced to death. Camus's conception of the absurd draws attention to the fact that, in a sense, everyone is sentenced to death as soon as they are born.
This apathy seeps through in the tonal quality of the narrative voice, as the novel invites readers to ask what a life amounts to without real and deep emotion? At the same time, considering the terrible situations Meursault encounters, a more emotional response would likely be highly negative, so Meursault’s apathy is perhaps preferable to any alternative. Either way, the apathy of Meursault juxtaposes against the gravity of the situations that Meursault finds himself in, all the way through his trial and death sentence.