On the train platform in Aleppo, Syria, Hercule Poirot talks to the burnished Lt. Dubosc without much zeal. Poirot is waiting to get on the train so he can get on the Taurus Express.
After leaving the Taurus Express, Poirot goes to the Tokatlian Hotel and learns he has to go back to London. He books a berth on the Orient Express. Then he meets his friend M. Bouc, and they see MacQueen and Ratchett talking.
Later the next day, on the train, Ratchett asks Poirot to protect him. He is afraid for his safety, after receiving a few unprepossessing and threatening letters. Poirot declines with out being plaintive or regretful.
The next morning, Poirot wakes up to see that the train has stopped. A great calamity has happened; the train is stopped by snow. M. Bouc privately tells Poirot that Ratchett has been murdered in his conpartment! He defrerntially asks Poirot to solve the case.
As part of the investigation Poirot and a doctor scrutinize Ratchett's conpartment. They hope to find an elucidation or clue as to who the murderer is. They see a cambric handkerchief and a pipe cleaner on the floor.
Poirot reads the burnt note on the floor of Racthett's compartment. He learns that Ratchett's real name was Cassetti, and he was the Armstrong Baby kidnapper!