Tony Wendice: How do you go about writing a detective story?
Mark Halliday: Well, you forget detection and concentrate on crime. Crime's the thing. And then you imagine you're going to steal something or murder somebody.
Tony Wendice: Oh, is that how you do it? It's interesting.
Mark Halliday: Yes, I usually put myself in the criminal's shoes and then I keep asking myself, uh, what do I do next?
Margot Mary Wendice: Do you really believe in the perfect murder?
Mark Halliday: Mmm, yes, absolutely. On paper, that is. And I think I could, uh, plan one better than most people; but I doubt if I could carry it out.
Tony Wendice: Oh? Why not?
Mark Halliday: Well, because in stories things usually turn out the way the author wants them to; and in real life they don't... always. Hmm. I'm afraid my murders would be something like my bridge: I'd make some stupid mistake and never realize it until I found everybody was looking at me.
C.A. Swan: Where's the nearest police station?
Tony Wendice: Opposite the church, two minutes walk.
C.A. Swan: Suppose I walk there now.
Tony Wendice: What would you tell them?
C.A. Swan: Everything.
Tony Wendice: Everything? All about "Mr. Adams" and "Mr. Wilson"?
C.A. Swan: I should simply tell them that you're trying to blackmail me into...
Tony Wendice: Into?
C.A. Swan: ...murdering your wife.
Tony Wendice: [laughs] I almost wish you would. When she heard that we'd have the biggest laugh of our lives.
C.A. Swan: Aren't you forgetting something?
Tony Wendice: Am I?
C.A. Swan: You've told me quite a lot tonight.
Tony Wendice: What of it?
C.A. Swan: Suppose I tell them how you followed her to that studio in Chelsea and watched them cooking spaghetti and all that rubbish. Wouldn't that ring a bell?
Tony Wendice: Oh, it certainly would. They'd assume you'd followed her there yourself.
C.A. Swan: Me? Why should I?
Tony Wendice: Why should you steal her handbag? Why should you write her all those blackmail notes? Can you prove you didn't? You certainly can't prove I did. It will be a straight case of your word against mine.
C.A. Swan: Smart, aren't you?
Tony Wendice: No, not really. I've just had time to think things out. Put myself in your position. That's why I know you're going to agree.
C.A. Swan: What makes you think I'll agree?
Tony Wendice: For the same reason that a donkey with a stick behind him and a carrot in front always goes forwards and not backwards.
C.A. Swan: Tell me about the carrot.
Tony Wendice: One thousand pounds, cash, to be placed in an account under your name. That ought to appeal to you — you've been skating on some very thin ice.
C.A. Swan: [evasive] I don't know what you mean...
Tony Wendice: You should. It's been in all the papers. A middle-aged woman found dead in her London flat of a drug overdose. Apparently, she'd been taking the stuff for quite some time, but no-one seems to know where she got it. [smiles] But we know, don't we? Poor Miss Wallace.
C.A. Swan: When would this take place?
Tony Wendice: Tomorrow night.
C.A. Swan: Tomorrow! Not a chance! I've got to think this over.
Tony Wendice: It has to be tomorrow. I've arranged things that way.
C.A. Swan: Where?
Tony Wendice: Approximately where you're standing now.
Chief Insp. Hubbard: Sooner or later, he'll come back here. As I've pinched his latch key, he'll try the one in the handbag. When that doesn't fit, he'll realize his mistake, put two and two together, and look under the stair carpet.
Mark Halliday: If he doesn't do that, all of this is pure guess work. We can't prove a thing.
Chief Insp. Hubbard: That's perfectly true. But once he opens that door, we shall know everything.
[Hubbard has just explained Tony's plan]
Margot Mary Wendice: How long have you known this?
Chief Insp. Hubbard: Did you suspect it yourself?
Margot Mary Wendice: No, never. And yet... What's the matter with me, Mark? I don't seem able to feel anything.
[Tony has just been caught]
Tony Wendice: As you said Mark, it might work out on paper, but... Congratulations, Inspector. Oh, by the way... [makes himself a drink] How about you, Margot?
Margot Mary Wendice: Yes, I could do with something.
Tony Wendice: Mark?
Mark Halliday: So could I.
Tony Wendice: I suppose you're still on duty, Inspector.