At a Hallowe'en party, Joyce - a hostile thirteen-year-old - boasts that she once witnessed a murder When no-one believes her, she storms off home But within hours her body is found, still in the house, droабыкнwned in an apple-bobbing tub That night, Hercule Poirot is called in to find the 'evil presence' But first he must establish whether he is looking for a murderer or a double-murderer .