Dumb Witness (S06E04)

Mystical premonitions, family inheritance and suspicious murders ruin Poirot's plans to go and watch a friend of Hastings' attempt to break the world water speed record. The Tripp sisters' supernatural warnings and Poirot's advice to change her will, fail to prevent the murder of Emily Arundel. Poirot must reflect on which member of the family poisoned the medicine. Bob, the terrier dog, is the only one who knows who the murderer really is. (iTunes)