Believe me, I can't tell you, I would if I could.
3 seconds sound clip from the The Curse of Frankenstein movie soundboard.
You can hear this line at 00:25:58.450 in the Blu-ray version of the movie.
Quote context
[...]
- I can't explain, but it will not be safe here.
- Not safe? Victor will be here all the time, won't he?
- Oh, yes. Victor will be here.
- It's because of Victor that I'm asking you to leave.
- He's conducting a series of experiments which could be extremely dangerous.
- You wouldn't understand, sufficient to say that.
- I would understand, I'm sure I would. Please, tell me.
- Believe me, I can't tell you, I would if I could.
- Then I shall have to ask Victor. If I'm to marry him, then I have a right to know.
- Marry?
- Of course, we're engaged. Didn't he tell you?
- How can you be engaged to someone you don't even know?
- It was an arrangement between Victor and my mother.
- That's absurd. You can't be expected to honor an arrangement of that sort.
[...]