Elinor receives an anonymous letter warning her that Mary Gerrard is trying to usurp her place in Laura Welman’s household. Laura had always taken a strong interest in Mary, sending her the best schools and abroad for her education, and really treating her as if she were her own child. Now that he’s had a stroke and is bedridden, Mary is with Laura constantly.
When her aunt dies interstate, Elinor inherits the whole of the £200,000 estate. It had always been expected that she and her cousin Roddy would each be willed half of it and that it wouldn’t matter anyway because they intended to marry. Now that seems to be dashed as Roddy confesses he doesn’t love Elinor and won’t simply marry for money. He’s not sure if he loves Mary, but he thinks he might.
Mary is poisoned to death. Only three people could have done it — Elinor, Nurse Hopkins, or Mary herself — but the only one with a motive is Elinor. Laura Welman’s body is exhumed and it’s discovered that she, too, was poisoned with a morphine overdose.
Not the most difficult mystery in the world. Laura treated Mary like her own daughter; I suspected right away that that’s what she was. Enter Lewis and there you go. Who is the murderer? Well, only two real possibilities, the doctor who engaged Poirot’s services (not though that would rule him out) or Nurse Hopkins. The one would be motivated for love, the other for money. When needle marks are discovered on Hopkins’s arm it rather suggests she’s acquainted with morphine.