Lucy Crale: I've heard about you. The things you've done. The way you work. It's psychology. It's your forte, n'est-ce-pas?
Hercule Poirot: C'est vrai. My success, it is founded in psychology, or, the 'Why?' of human behavior."
[Pointing to his head]
Hercule Poirot: It is this that I use.
Hercule Poirot: It is surprising, is it not, how soon in life the die is cast.
Hercule Poirot: The truth, it has the habit of revealing itself...
Hercule Poirot: Human nature has an infinite capacity to surprise.
Amyas Crale: Living in a house full of women is enough to send any man off his chump.
Hercule Poirot: Hercule Poirot: You kill her, you kill yourself.