When Lydia Langstone flees her abusive husband, she seeks refuge in the gloomy lodging house of her elderly father. But #7 Bleeding Heart Square is home to a dark mystery. Where is Miss Penhow, the middle-aged spinster who owns the house, but hasn't been seen for four years? Why does a seedy plain-clothes policeman watch the square so obsessively? And who is sending parcels of rotting hearts to the house?