Poirot and Hastings are invited to watch Charles Arundell, a friend of Hasting's, to watch as he attempts to break a water speed record on a lake. Unfortunately, his boat's engine falters, and he has to jump out.
At a reception later, the guests overhear Charles' aunt refuse to give him any more money for the boat. That night, she is nearly killed when she falls down a flight of stairs. Her dog Bob's (Spunky) ball on the stair is blamed.
Aunt Emily tells Poirot that she's afraid one of her heirs is trying to kill her. He advises her to change her will and leave all of her money to a friend, not tell the friend, but tell the relatives. This way, they won't hurt her, hoping that she will change her mind at some point.
Emily takes his advice, but dies very suddenly. Poirot believes she was murdered and undertakes to investigate, since the local authorities refuse to do an autopsy. Poirot temporarily becomes Bob's owner as well. It's a good match. Poirot believes the dog knows who killed his owner and in time, will give him the evidence he needs.
Clever and entertaining film, and who knew that fastidious Poirot could be fond of a dog, albeit an irresistible one? The Fox terrier breed was popular in the '20s and '30s. It's odd how breeds go in and out of fashion.
There are plenty of suspects, and you'll go from one to the other as Poirot sits through a couple of séances, learns of another murder, and finally refuses to leave for London until a very important matter is settled.
Delightful episode, and a real favorite of mine.