In "The Demon Lover," Mrs. Drover has returned to her London home to collect some belongings for herself and her family. (They fled this house when the war began and moved out to the country where the German bombs could not reach them.)

Mrs. Drover has clearly not visited this house for some time: it is shuttered, the air is stale, and the remaining possessions are covered in a film of dust. While collecting the items she requires, Mrs. Drover notices that somebody has left a letter for her on the hall table. This letter appears to come from her former fiancé, a soldier who was reported missing during the war, and who has returned to keep an appointment that they made twenty-five years ago. 

Mrs. Drover flees the house with the items she has come to collect, without realizing that she has walked straight into the arms of her demon lover.  

Why does Mrs. Drover return to the house in "The Demon Lover"?

It is World War II, and the Germans are bombing London on a regular basis. Like many other Londoners, Mrs. Drover and her family have escaped to the countryside. Mrs. Drover is in the city for a day in August to do some shopping and decides to return to her London house to look for some family belongings and personal items that she wants to take away.

The setting of the blitz becomes the eerie and fitting backdrop to this ghost story. All the familiar domestic surroundings have become defamiliarized and made unhomelike by the war. The street is deserted, and Mrs. Drover's house is boarded up, empty, and dark. Even the caretaker is away on vacation. As she reads the letter mysteriously left in the hallway, rain pours down outside.

This strange environment, in which the recent past seemed erased, brings up Mrs. Drover's repressed memories of twenty-five years past, when in 1916 her lover went missing in World War I, presumed dead. It seems he has returned, just as a world war has returned, and is here to haunt her. She has moved on with her life, marrying and having three children, but has not entirely moved on, as her desire to look for "several things she wanted to take away" symbolizes. She has not yet let go of her past.