Mrs Ludlow is hated because of her arrogance and cruelty towards her children, whose lives she dominates. When a body turns up, all think Mrs Ludlow must be the murder victim. But it is actually her housekeeper who has been found dead. Has a mistake been made and the wrong woman killed? Dr Patrick Grant uses his powers of logic and deduction to determine this is not the case, but he can only prove it at the expense of incriminating an innocent person. How will he solve this particular conundrum?