An aging country gentleman reads one too many chivalric romances, loses his grip on reality, and sets out to become a knight-errant — recruiting a bewildered farmer as his squire and mistaking windmills for giants, inns for castles, and sheep for armies. What starts as a joke about a man who can't tell fiction from life becomes something stranger: a portrait of stubborn idealism that refuses to stop being funny, or moving.
Widely considered the first modern novel — the book that invented the idea of a character whose inner delusion is more interesting than the world around him, and that has shaped every unreliable hero since.