Five Little Pigs

In this 1942 novel, the true killer is revealed to be Caroline Crale's teenage half-sister, Angela Warren. Caroline Crale had intentionally taken the blame and allowed herself to be convicted to protect Angela, who had tampered with a beer bottle out of childish spite. Hercule Poirot uncovers this truth by interviewing the five surviving witnesses sixteen years after the murder.

The victim is Amyas Crale, a brilliant but selfish English painter. He was poisoned with hemlock while painting a portrait at his country home. His wife, Caroline, was famously convicted of the crime, which Poirot is hired to reinvestigate.

Because the murder happened sixteen years prior, Poirot does not examine the physical crime scene. Instead, he relies purely on psychology by interviewing the five surviving witnesses who were present the day Amyas died. He compares their written accounts to their verbal testimonies, finding the psychological contradictions that reveal the truth.

Agatha Christie cleverly based the novel's structure on the classic nursery rhyme 'This Little Piggy.' Poirot characterizes each of the five suspects based on the lines of the rhyme, such as one going to market and another staying home. The title directly refers to the five suspects whose intertwined secrets Poirot must untangle.