The Strangers in the House, by Georges Simenon

Hector Loursat may represent at some level pre-war French existential paralysis. In Moulins, where he practiced law, but now sits all day in his study poking his fire, reading his books and drinking his burgundy, it is winter, dark and moody. The large house in which he has confined himself to two rooms is drafty. It holds secrets up on the third floor. Those secrets eventually draw out misanthropic Loursat to once again practice law. But this is not primarily a story of a murder investigation. Rather, it is an exploration into the mind of a man who emerges from 18 years of self-imposed isolation. Structurally, the story's tempo is rapid and regular enough to keep your attention. Moreover, its introspection may inform the reader's own life - a mark of a great read.