S12, E1: Poirot attends a dinner party hosted by his friend, retired actor Sir Charles Cartwright, and finds himself a witness to murder. A local clergyman chokes to death on his cocktail, but Poirot cannot determine how foul play occurred, since almost any one of the guests might have taken the lethal glass. He cannot find a trace of poison or an obvious motive for murder among the guests, who include an enigmatic ingenue, an inquisitive playwright and doctor Sir Bartholomew Strange. But weeks later, Strange chokes to death at his own dinner party - which boasts many of the same guests. This time a mortuary report confirms that Strange was poisoned - and there seem to be plenty of people who wished him ill. Could the missing butler, mysterious telephone message or secret tunnel have a bearing on the case? It takes another death before the impossibility of the first murder begins to make sense. Can Poirot and his little grey cells tie all the evidence together and reveal the killer?