# Explanations explained — The Mystery of the Blue Train

> Chapter companion for The Mystery of the Blue Train by Agatha Christie.

## What happens

Poirot explains to Van Aldin how he solved the murder of Ruth Kettering. He reveals that the crime was committed by Major Knighton and Ada Mason (actually Kitty Kidd), who worked together. Knighton, posing as Van Aldin's secretary, boarded the train, strangled Ruth, and took the rubies. Ada Mason impersonated Ruth to mislead the conductor, and the face was disfigured to prevent identification. Poirot also notes Knighton's limp was faked and that he fell in love with Katherine Grey, leading him to frame Derek Kettering.

## Themes in this chapter

### Deception and Appearances

The entire crime hinges on disguise and false identities: Ada Mason impersonates Ruth, Knighton fakes his limp, and both conceal their true roles.

### Justice and Morality

Poirot's methodical unraveling of the truth brings justice for Ruth Kettering, despite the elaborate deception.

### Greed and Materialism

The murder is motivated by the desire for the rubies, and Knighton's elaborate scheme is driven by greed.

## Character check-ins

### Hercule Poirot

Provides the full explanation of the murder to Van Aldin, detailing his deductive process.

### Rufus Van Aldin

Listens to Poirot's explanation, expresses gratitude and relief.

### Major Knighton

Revealed as the mastermind behind the murder, working with Ada Mason; faked his limp and framed Derek Kettering.

### Ada Mason

Revealed as the accomplice (actually Kitty Kidd), who impersonated Ruth Kettering on the train.

### Katherine Grey

Mentioned as having sensed Ruth's presence and acted on her intuition about Knighton's guilt.

### M. Papopolous

Encountered by Poirot in the hotel lounge; implicated in selling a ruby to Mirelle.

## Key lines

> It began with the one point that puzzled me. You know what that point was? The disfigured face.

Poirot explains that the disfigured face was the first clue that made him question the victim's identity.

_Poirot's initial suspicion about the crime._

> I am a good detective. I suspect. There is nobody and nothing that I do not suspect. I believe nothing that I am told.

Poirot emphasizes his method of questioning all evidence and testimony.

_Poirot's detective philosophy._

> There was no man. Ah— mille tonnerres! —do you not see the cleverness of it all?

Poirot reveals that the man seen on the train was a fabrication by Ada Mason.

_Key twist in the explanation._

> Miss Grey is not a fanciful woman by any means, yet she firmly believes that she felt your daughter’s presence beside her one day in the Casino Gardens at Monte Carlo.

Katherine Grey sensed Ruth Kettering's spirit trying to communicate the identity of her murderer.

_Supernatural element in the investigation._

## Links

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- Book: https://www.betterreads.online/discover/the_mystery_of_the_blue_train_se
- All chapters: https://www.betterreads.online/discover/the_mystery_of_the_blue_train_se/chapters