Murder Was My Neighbour — Guy Cobden

One-time policeman and Private Inquiry Agent John Chadwick was renting a house by the sea's edge when he saw a neighbour behavingmysteriously - and felt impelled to investigate. The trail took him to London and to victims of a blackmailer. Hard businessman George Swinton has a plan - if he can get the co-operation of the other victims. Chadwick gets many shocks as he probes deeper into the mystery, but none as great as the final one, when he learns the real reason for the house by the sea wall.