This was one of the first crime novels to feature rail transport. That murder could be committed on the new railways of France was something of a shock. Not only that, the main characters all worked on the railway and much of the action takes place as they go about their daily work. Zola spent a lot of time researching the operation of the railways so that he became intimately familiar with them. He studied not only its functioning (how to drive an engine, how signals work, how to maintain an engine) but also the jobs involved and the training required to do them. Some critics feel that he became so fascinated by railways that he spends too much time in this book describing them, but that apart, the book is a real cracker!
Sometimes translated as The Beast Within, it is certainly gory in places and feels as though it could have been written in the late twentieth century, except for mention of horses on the roads and the lighting of candles in the houses.
The central character has much in common with Dr Jekyll, struggling to keep at bay his inner Mr Hyde. This man’s inner beast is one who cannot help killing the women he loves, which presents a fascinating and very tense atmosphere as he falls in love with the wife of an engine driver. But how will he (they) get rid of the husband? Has this man committed murder already as the body of a member of parliament is discovered lying alongside a railway track? Who is this seemingly ordinary man who cannot control his need to kill?
As with all Zola’s works, this one has a pace that kindles the reader’s need to know the next episode. Just as Agatha Christie reserved her biggest surprises for the end, so does Zola. I recommend reading it in the original if possible.