On the face of it this is a film about the life and death of a donkey called Balthazar near the Pyrenees, from the time it's young and searching for its mother's teat to its death in a field surrounded by sheep. In between these two extremes we have other extremes: the young Marie loving it in idyllic scenes, and the older Marie (Anne Wiazemsky) meeting it on various occasions; its life as carrying bread for a baker and being ill-treated by the baker's delivery youth Gérard (François Lafarge), who is no more than a heartless thug; and Bathazar being used by a miller (Pierre Klossowski) with a whip to make the animal turn the stones faster.
But, of course, there's more here than that, as the name of one of the magi – Balthazar – should suggest. The mule is a spiritual, indeed Christ-like figure, as borne out by the many religious allusions: the young Marie baptising it, the stations of the cross, the seven deadly sins, its 'crucifixion', the flock looking over its death, and so on.
At about ninety minutes, a great deal is packed into this film: a murder, a doomed love affair with the leader of the gang (Gérard with Marie), a lost-suffering and finally unconsumated lover of Marie (Jacques (played by Walter Green)), Arnold (Jean-Claude Guilbert) the down-and-out alcoholic suspected of murder, Marie sort of prostituting herself and later being beaten up by the gang of thugs, and a number of other events.
All this is in Bresson's austere black and white style, with expressionless lines from non-actors, a lack of artifice, and a truly wonderful film all round.