Fear Stalks the Village: Ethel Lina White (British Library Crime Classics, Band 122)

It was a model English village, filled with flowers, Tudor cottages, and cobbled streets. Joan Brook loved working there as a companion to Lady d'Arcy, living in the huge mansion with its surrounding park. And small though the village was, it was not too small for Joan to have found a man there whom she could love. Suddenly the peaceful surface of life there is shattered as a poisonous letter is received by the town's most saintly citizen. It is followed by others; no one is safe from the anonymous letter writer. And the letters bring death. In the anguished days that follow, Joan realizes her own danger. For to receive on of these letters could mean the end of her love - and her life!