Calamity at Harwood — George Bellairs

To solve a murder case, Thomas Littlejohn contends with ghosts, Nazis, and crooked real estate speculators

Known across London as one of the premier slumlords of the East End, Solomon Burt has never fallen in love with a property the way he has with Harwood, a faded manor house halfway between London and the sea. When the owner refuses to sell, Burt uses every trick he knows to buy the house out from under the man and convert it into apartments. Now Burt owns the property lock, stock, and barrel -- but he will have to share it with the ghosts.

When Burt is found murdered, the tenants fear a ghost might be responsible. Detective-Inspector Littlejohn is called down from London to solve the case and restore reason. But what he find lurking in the back corners of Harwood is far more dangerous than a poltergeist.