Castle: If you found out a man was cheating on you, how would you kill him?
Martha: Knife... to the heart.
Castle: All right. What if you don't have the stomach for that?
Alexis: Shoot him.
Castle: But you don't have the stomach for that either.
Martha: What's wrong with our stomachs?
Alexis: There's always poison.
Martha: True. Watch him writhe and suffer.
Alexis: Die like the rodent he is.
Castle: Wow. All these years writing about murderers, I had no idea I was living among them.