A shipping clerk living in French Algiers in the 1940s, Meursault is a young, detached but ordinary man. The novel begins with Meursault receiving a telegram informing him of his mother's death. He attends the funeral, but surprises other attendees with his unusual calm and (once again) detachment.
Over the next two weeks, Meursault carries on life as if nothing tragic has happened. He frolics with a new girlfriend, befriends a pimp, and goes on a beach vacation with both. It's almost like this guy is strangely detached or something.
During the beach vacation, however, Meursault and friends are confronted by two Arabs. Violence ensues, with Meursault eventually killing one of the Arabs. It was a hot day, and aside from the weather, no explanation exists for Meursault's crime.
At his murder trial, the court seemed much more interested in Meursault’s lack of grief over his mother's death than the alleged heinousness of his crime. Judged to be a cold-hearted, nonconforming, and of course, detached misanthrope (hater of humankind), the jury finds Meursault's character—not crime, per se—punishable by death.
Awaiting his execution in prison, Meursault struggles to come to terms with his impending death. One day, after becoming enraged with an annoying, preachy chaplain, Meursault denounces Christianity and vehemently refuses to appeal to religion as a way of finding solace. Meursault joins the absurdist camp when he declares that 1) the world is meaningless, lawless, and without rational order, and 2) this is a perfectly justified claim.
Some would say he gets "enlightened" in prison. Others would disagree. Either way, Meursault looks forward to his execution as affirmation of his "life is ridiculous" mantra. At the very least, he gets to leave society and all that goes with it behind.