- Well, I'm not afraid of you.
- Why not? For all you know, I murdered a woman.

5 seconds sound clip from the The 39 Steps (1937) classic radio play.

You can hear this line at 00:30:54 in the radio play.

Quote context

[...]

- Ha ha. I don't believe you.

- All right, very well then. I'm just a plain, common murderer who stabbed an innocent, defenceless woman in the back in Portland Place, London.

- I don't know how innocent you may be... but you're a woman, you're defenceless, and you're alone on a desolate moor in the dark.

- And you're manacled to a murderer who would stop at nothing to get you off his hands.

- If that's the story you prefer, have it, my lovely, and welcome.

- Well, I'm not afraid of you.

- Why not? For all you know, I murdered a woman.

- You listen to a bit of advice. From now on, you do everything I tell you to do and do it quickly.

- Oh, you wretched bully.

- I admire your pluck, but you keep a civil tongue in your head. Otherwise, I might feel the next killing was a bit overdue.

- All right, on your feet now.

- Well, where are we going?

- I see some lights over that way. We'll do a little investigating.

[...]