What you have to face reading this relatively short story by Henry James is that it is going to take a while because of the language. He uses very stilted phrases that prevent this from flowing.
The only reason this book manages to keep your attention is because underneath the painful construction of the text is a solid story. The mix of the supernatural and the aristocracy is a well used one but never fails to get the hairs on the back of your neck going if done well.
This takes a while to get going with the story being related second-hand at a meeting of friends in the country. One of the guests promises an account of something so disturbing that the rest of the company will never forget it based on the idea of a child being connected with a ghost.
So the story of a governess sent to a large house in the country to look after two children unfolds. The children are angels and yet there is something troubling the governess who is informed that the older of the two, the boy, has been expelled from school.
Tales also of the former governess dying shroud the house in some sort of darkness.
But things get moving when the governess comes across a stranger walking in the grounds, a stranger not to the rest of the staff, who describe him as the former man servant for the owner. So far creepy but no problem but then the screw gets turned with the revelation that the man the governess saw is a ghost.