He should marry her.

And she would keep the key of that iron box with the diamonds, and he should find what sort of a noise she would make if he attempted to take it from her.

She closed the morocco case, ascended with it to her bed-room, locked it up in the iron safe, deposited the little patent key in its usual place round her neck, and then seated herself at her desk, and wrote letters to her various friends, making known to them her engagement.

Hitherto she had told no one but Miss Macnulty,--and, in her doubts, had gone so far as to desire Miss Macnulty not to mention it.

Now she was resolved to blazon forth her engagement before all the world.
The first "friend" to whom she wrote was Lady Linlithgow.