<p> 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, drowned in an apple-bobbing tub. </p> <p> 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.? </p>