If you listen closely, the muffled voice in the teaser says: "The terrace and the whole place, the lawn and the garden beyond it, all I could see of the park, were empty with a great emptiness."
If you look up the quote it's from the 1898 horror story The Turn of the Screw by Henry James.
And, if Season 1 is any indication, the setting will once again be extremely important. So, The Turn of the Screw takes place in a London country house named Bly Manor.