As a representative of the Gothic genre, the pervasive tone and mood of the novel The Turn of the Screw reunite the following qualities:

psychological (more so than physical) isolation- The governess is not just isolated physically along with the children and the staff of the estate. She also suffers from a mental agony where she wonders whether she is right or wrong. Not even the reader can make a clear decision about this.

sadness and nostalgia- at all times there is a reminisce of the past, either by constantly describing the estate as old and once majestic, or by memories of things that happened before. Moreover, the fact that the governess is left to her own devices with children at a cold, barren place, evokes sentiments of abandonment. 

inevitability of fate- the fact that the antagonists of the novel are ghosts (or so the governess claims) makes it impossible to defeat them. Toward the end of the novel, getting rid of the ghosts at all costs becomes the obsession of the governess and, as a result, tragedy ensures. 

The tone is indicated by the mood, therefore you will find:

-darkness and coldness- in the never-ending winter that pervades the area 

-lack of order- the entire household was at the mercy of a woman who was too young and unprepared for what was going on.

-tragedy- in the end there is nothing that the woman could have controlled. All turns out badly and the ending is quite tragic. 

You will find that the mood and tone of Gothic literature is very salient and easy to repeat over and over, which in part is why it is such a popular genre.