Ah, now I get the Heyer love. Picked this up because several of my GR and BL friends swear by Heyer. It was enjoyable. More of a domestic drama than a flat out mystery. It's like a forerunner of Ruth Rendell when she is/was writing as Barbara Vine.
Heyer looks at a family that is under the thumb of the worst Dickens character ever (think an evil Martin Chuzzlewit). Then the horse manure hits the fan. It's actually quite a good book with nice little touches.