Now I understand it: Cagliostro is not only an impostor--a charlatan, but he is a thief and an assassin.

I have been caught in the trap set for me, like a credulous fool! He and his associates will rob me and plunder my beautiful villa, but just given to me, and, when they have secured all, murder me to escape betrayal." With deep contrition, weeping and trembling, Wilhelmine accused herself of her credulity and folly.

For the first time in her life she was dismayed and cowardly, for it was the first time that she had had to tremble for her possessions.
It was something so new, so unaccustomed to her to possess any thing, that it made her anxious, and she feared, as in the fairy tale, that it would dissolve into nothing.

By degrees her presence of mind and equanimity were restored.

The stillness was unbroken--and no one forced the door, to murder the mistress of this costly possession.