: Still feeling guilty for disfiguring Angela years ago, Caroline deliberately staged the scene to look like a suicide and went to the gallows without a fight to "pay her debt" and protect her sister from a crime she didn't commit.
Poirot investigates by interviewing the five other people present on the day of the murder:
: The devoted governess who witnessed Caroline's behavior at the scene. [S9E1] Five Little Pigs
: A stockbroker and Amyas’s best friend. In the TV adaptation, he was secretly in love with Amyas.
Poirot concludes that while Elsa got what she wanted—Amyas's death—she ended up with a "living death," spending her life in bitter emptiness while Caroline died at peace. : Still feeling guilty for disfiguring Angela years
Through his psychological analysis of their testimonies, Poirot discovers a heartbreaking truth:
: Caroline’s younger half-sister, whom Caroline had accidentally disfigured as a child. The Twist Ending In the TV adaptation, he was secretly in love with Amyas
: Elsa Greer killed Amyas. She overheard him tell Caroline that the affair meant nothing and that he intended to send Elsa away as soon as the painting was finished. Spurned and vengeful, Elsa poisoned his beer.