Yes, 'Murder on the Orient Express' was inspired by a true story. Agatha Christie drew on real - life events and her own experiences during her travels. However, she added her own fictional twists and turns to create the captivating mystery novel we know today.
The character of Ratchett is crucial. He is the victim, but as the story unfolds, we learn that he is not as innocent as he might first appear. His past actions seem to have led to his untimely death on the train. All the characters' backstories and relationships play a vital role in making the plot of 'Murder on the Orient Express' so engaging.
Colonel Arbuthnot is also among the main characters. He is a military man, and his relationship with some of the other passengers and his actions during the investigation play an important role in uncovering the truth about the murder on the Orient Express.
The main character is Hercule Poirot, the brilliant detective. And there are the various passengers on the Orient Express, like Ratchett, who is the murder victim.