She was killed by a foreign agent who was trying to steal it.
5 seconds sound clip from the The 39 Steps (1937) classic radio play.
You can hear this line at 00:22:13 in the radio play.
Quote context
[...]
- What about our mutual friend, Annabella?
- The police are looking for you.
- Yes, but I didn't do it. I...
- But why come all this way to Scotland to tell me about it?
- Well, I believe she hoped to come see you about some Air Ministry secret.
- She was killed by a foreign agent who was trying to steal it.
- Oh. Did she tell you what this foreign agent looked like?
- Oh. Oh, yes, there was... There was one thing.
- She told me the top of his little finger is missing.
- Are you sure it wasn't on the right?
- Good Lord. Then you're...? You're the one she...?
- The one she was trying to warn you against. The chief.
[...]