The Card Players is one of Cezanne’s best-known pictures, but it is also one of his most mysterious. Why did the so-called father of modern art paint two old men hunched over a game of cards? What is the picture trying to tell us? By exploring Cezanne’s puzzling religious beliefs and his passion for Mary Magdalene, the patron saint of Provence, Waldemar Januszczak uncovers the surprising secrets of a haunting masterpiece.