Poirot and Hastings are in Windemere watching Charles Arundel's attempt to break the world water speed record. They return to the Arundel's family members. The situation is exasperated when Aunt Emily falls down the stairs. Poirot suspects foul play and his suspicions are confirmed when she is found dead the following day. It becomes clear to Poirot that the only one who knows who murdered Emily is Bob, the resident fox terrier. Poirot understands that this dumb witness must find his own way of telling him what he has seen.