Pierre Michel is Susanne's father.

Pierre Michel, the Wagon Lit conductor on the Simplon Orient Express, was the father of Susanne, the French nursemaid who threw herself from a window after being wrongly suspected of complicity in the kidnapping and murder of little Daisy Armstrong. This familial bond, rooted in the tragedy that destroyed the Armstrong household, provided the personal motive that drew Michel into the elaborate conspiracy of twelve passengers to execute Samuel Edward Ratchett, the man who had escaped justice for the crime. Michel's role was not merely that of an accessory; his position as conductor on the very train where the murder was staged was essential to the plan's execution, and his daughter's fate made him a willing participant in the collective act of vengeance.

Identity and Background

Pierre Michel was a Frenchman who lived near Calais and had been employed by the Compagnie Internationale des Wagons Lits for over fifteen years. He was described by M. Bouc, a director of the company, as thoroughly respectable and honest, though not remarkable for brains. His daughter, Susanne, had been the nursemaid in the Armstrong household, devoted to little Daisy Armstrong. After the kidnapping, the police were convinced that Susanne had some knowledge of the crime and refused to believe her hysterical denials. In a fit of despair, the poor girl threw herself from a window and was killed. It was proved afterwards that she had been absolutely innocent of any complicity in the crime. This injustice, the death of his only child, became the driving force behind Michel's involvement in the plot.

Role in the Conspiracy

Michel's position as the conductor of the Stamboul-Calais coach was indispensable to the conspirators' plan. The murder was deliberately staged on the Orient Express because Michel worked on that route, providing an insider who could facilitate the crime and help ensure that suspicion would not fall on the passengers. The plan required that every compartment in the Stamboul-Calais coach be occupied by a member of the conspiracy, and Michel was responsible for managing the bookings. When a last-minute passenger, Hercule Poirot, boarded the train, Michel was forced to accommodate him, a complication that the conspirators had not anticipated. During the night of the murder, Michel's actions were carefully coordinated with the others. He left his seat at the end of the corridor to speak with his colleague in the Athens coach, creating a window of opportunity for the conspirators to enter Ratchett's compartment. He also answered the bell from Princess Dragomiroff, who had summoned her maid, Hildegarde Schmidt, as part of the alibi structure. Michel's own alibi was provided by the other two conductors, who confirmed that he was with them in the next coach for a period around one o'clock.

The Discovery of the Crime

It was Michel who discovered the body the following morning. The valet, Edward Masterman, had tapped several times at Ratchett's door with no answer. Later, the restaurant car attendant wanted to know if Ratchett was taking lunch. Michel opened the door with his key, but found the chain fastened. After getting the chef de train, they broke the chain and entered. Michel found Ratchett dead, stabbed multiple times, with the window open and snow drifting in. He was visibly shaken by the discovery, described as white as chalk, and buried his face in his hands. During the subsequent investigation, Michel was initially suspected when a button from a Wagon Lit tunic was found in Mrs. Hubbard's compartment. He vehemently protested his innocence, and his alibi was confirmed by the other conductors. The button was later revealed to have been dropped by the conspirator who had disguised himself as a conductor.

Revelation and Aftermath

Poirot deduced Michel's connection to the Armstrong case when he realized that the dead nursemaid had been French. He reasoned that if Susanne were Michel's daughter, that would explain everything, including the choice of the Orient Express as the setting for the crime. When Poirot presented his second solution to the assembled passengers, Linda Arden, masquerading as Mrs. Hubbard, confirmed the details. She stated that there had been twelve of them, or rather eleven, as Susanne's father was over in France. She explained that they had a consultation with Susanne's father, who was willing to participate because Susanne had been his only child. Michel's role was thus not that of a mere accomplice but of a grieving father who had lost his daughter to the same tragedy that had destroyed the Armstrong family. In the end, M. Bouc and Dr. Constantine agreed to accept Poirot's first, more conventional solution, which exonerated all the passengers and attributed the crime to an outside assassin. Michel's complicity, along with that of the other conspirators, was officially concealed.