It was phantasmagorical.
Contains spoilers:
Some characters - Dani and Henry have their personal spectres, while there are also real ghosts in this story.
Dani stops seeing her dead fiancée after burning his glasses in the bonfire which proves the point that the spectre was in her head. After that she stops seeing him.
But I was confused whether Hannah Grose was already dead when Dani had arrived at the manor. If so how could she continue to act like she was still alive, making tea, cooking etc. The interaction between the ghosts and those alive was somewhat inconsistent.