YMMV / Sleeping Murder

• Complete Monster: Dr. James Kennedy, obsessed with his half-sister Helen, was furious when she opted to marry the father of young Gwenda Reed, and eventually murdered her, which a young Gwenda saw. Covering his crime by murdering Gwenda's nanny and drugging Gwenda's father, Kennedy framed him for murder, gaslighting him and hiding the body as to make him appear insane and have him sent to an asylum where he died. In the present, Kennedy murders the former maid when he fears she will implicate him and tries to poison Gwenda's household as well. Finally uncovered, he attempts to throttle Gwenda before Miss Marple herself intervenes.