Sir Charles Cartwright, Hercule Poirot and others in “Unfinished Business”

[after Poirot exposes him as the murderer] Well, I'm hooked. Go on. Tell me, what was my motive for murdering my dearest friend, the man I had known since boyhood?

Hercule Poirot

It was the doctor himself who gave to me the clue when he said, "Cherchez la femme." You know, Sir Charles, it was obvious to me you were in love, deeply in love with Mademoiselle Lytton Gore. You loved her with a passion that was so arid, so terrible. So why the hesitation, huh? Why did you not ask her to marry you when you were sailing around Loomouth? What was the obstacle, hein? Poirot, he will tell to you. The obstacle, it was this, that you already had a wife. Oh, but of course, you enact the role of the bachelor. But this marriage of yours it took place since many years before. When you were young. Long before you were Sir Charles Cartwright, the actor renowned. And when your name, it was something else. Voyez, mes amis. There are only two situations in the law of our land when a divorce, it cannot be permitted. The first: when either the husband or wife is serving a life sentence in prison. And the second: when one or either of them is confined to a lunatic asylum. And of course, Sir Charles, you cannot kill her yourself because immediately you would become the prime suspect. But what if nobody knew, hein? Well, then you'd be free to marry Mademoiselle Lytton Gore without having the need to tell her the truth. But one person did know and one person only. Your oldest friend. The best man at your wedding. And so, before you can remarry, it is necessary that Dr. Bartholomew Strange, your friend so dear to you, he must be eliminated.

And Babbington? I suppose he knew too?

Hercule Poirot

Ah, oui, that was the one flaw in my theory. Because even if it was you, Charles, who placed the liquid nicotine into the glass, you could never make sure of it reaching one particular person. No, the poison was never intended specifically for the Reverend Steven Babbington, no. It was intended for anyone who was there present. Except, of course, Dr. Bartholomew Strange, who never touched a cocktail, and Mademoiselle Lytton Gore, the young lady with whom you were in love.

You handed me my cocktail yourself.

Hercule Poirot

The murder of the Reverend Steven Babbington was nothing more nor less than a dress rehearsal. Sir Charles, he is the actor. He rehearses the murder before he commits it. And the rehearsal it goes well. Steven Babbington, he dies. And foul play, it is not suspected, not even by Hercule Poirot. Which is why, of course, I was invited to go to Loomouth. Because if Poirot suspects nothing, nor indeed will anyone else.