Complex sentence: She in the past had an affair with the rich and influential Grandmorin, and the jealous Roubaud forces her to meet him on a train, There he robs and kills his rival, but by chance the off-duty Lantier is a witness.
Split into simpler sentences: She in the past had an affair with the rich and influential Grandmorin. The jealous Roubaud forces her to meet Grandmorin on a train, There he robs and kills his rival, but by chance the off-duty Lantier is a witness.