Inscrutability

What about Mrs. Cavendish? I watched her as she sat at the head of the table, graceful, composed, enigmatic. In her soft grey frock, with white ruffles at the wrists falling over her slender hands, she looked very beautiful. When she chose, however, her face could be sphinx-like in its inscrutability.

The inscrutability of all this was the kind of inscrutability you have when you suddenly enter a room where a furious argument has just ended. Everyone is quiet. No one is talking.