Jean Renoir's "La Bête Humaine" is an excellent screen adaptation of Émile Zola's novel, which also contains some excellent photography and a fine performance by lead actor Jean Gabin. While usually overshadowed by Renoir's other more (justifiably) celebrated masterpieces, in itself it is a very good picture, with Zola's ideas and characters providing ideal material for the great director.
Most likely, the reason why "La Bête Humaine" is less appreciated than Renoir's other works is because it is so closely tied to the novel - which itself is actually part of a series of novels. Someone not familiar with Zola would find it harder to understand some of the action, especially the behavior of the main character, railway engineer Jacques Lantier (Gabin). There is a brief message at the opening of the film explaining the basic theme, but it would hardly be possible to bring an audience completely up-to-date with just a short note.
The novel on which the film is based is part of a series of 20 novels that Zola wrote, which cover the history of a single family through several generations and through several decades of 19th-century French history. Each of these stories is capable of standing on its own, but they are more satisfying if you know at least something of the broader context. "La Bête Humaine" is one of the last few volumes in the series, and accordingly, it largely assumes a familiarity with the basic themes. Zola had two main concerns in these novels: (i) to show how certain family traits (positive and negative) re-appear in successive generations, and (ii) to show how the lives of a particular family reflect events and trends in French society as a whole. Zola was a naturalistic writer - he had a strong sense of identification with and sympathy for his characters, but he also portrayed his characters and his country in an uncompromising light, just as they were.
There are at least a couple of ways that this context helps better to appreciate the film version of "La Bête Humaine". First, Jacques Lantier comes from a branch of the family that was particularly plagued with mental instability. He has many positive qualities, but also is tormented by barely-suppressed violent urges. Gabin does an excellent job (as he always does) of portraying his character, but some of it is lost if the viewer is unaware of who he is supposed to be. Second, the railway setting, interesting in its own right, is meant to be suggestive of other forces, both within Lantier's mind and also outside of his life. (The action in this story is supposed to have taken place in about 1870, a tumultuous time in French history.)
All of this comes together in the outstanding opening sequence, which shows Lantier's train rushing across the countryside. The beautiful photography and skillful editing help us to feel as if we were in the train with him, and all of this is supposed to suggest not just the setting of the story to come, but also the powerful forces - both inside Lantier and outside of him - which he cannot control.
All of the subsequent plot developments - interesting and sometimes surprising in themselves - build on this foundation. This is nicely and carefully done, even if some of it is unfortunately lost if the viewer does not know a little of the wider context.
