# A New Theory explained — The Mystery of the Blue Train

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

## What happens

Poirot meets with Van Aldin and Knighton to propose a new theory that Derek Kettering may not have murdered his wife, suggesting instead that the Comte de la Roche could be responsible after Poirot successfully upsets his alibi. Van Aldin, initially resistant, agrees to travel to the south of France with Poirot to investigate further.

## Themes in this chapter

### Justice and Morality

Poirot's pursuit of a new theory reflects the theme of seeking true justice rather than accepting a convenient solution.

### Deception and Appearances

The chapter challenges the apparent guilt of Derek Kettering, suggesting that appearances may be deceiving and that the real culprit might be the Comte de la Roche.

## Character check-ins

### Hercule Poirot

Presents a new theory exonerating Derek Kettering and proposes traveling to the south of France.

### Rufus Van Aldin

Reluctantly agrees to accompany Poirot to the south of France to investigate the new theory.

### Major Knighton

Present during the meeting; expresses surprise at the new theory and mentions having seen Katherine Grey.

## Key lines

> If I had had an idea of this,” he groaned. “I wish to God I had never got that little Belgian to ferret out the truth. Find Ruth’s murderer—that was all I thought about.”

Van Aldin regrets hiring Poirot, wishing he had never involved him in uncovering the truth about Ruth's murder.

_Van Aldin expresses regret over the investigation's direction._

> Supposing, I say, that Monsieur Kettering did not murder his wife?”

Poirot proposes the possibility that Derek Kettering is innocent of his wife's murder.

_Poirot introduces a new theory exonerating Derek._

> There is an off-chance,” he said quietly, “that it might be the Comte de la Roche after all. At least I have succeeded in upsetting his alibi.”

Poirot suggests the Comte de la Roche could be the murderer, having successfully discredited his alibi.

_Poirot shifts suspicion to the Comte de la Roche._

## Links

- HTML: https://www.betterreads.online/discover/the_mystery_of_the_blue_train_se/chapters/xxxiii-a-new-theory
- 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