 This, coupled with some unwittingly suggestive comments from Byne, leads Wolfe to identify the murderer.Summoning the guests to his office, he has them reenact the circumstances under which Faith Usher received the poisoned champagne multiple times.This demonstrates that Mrs. Robilotti's son Cecil, who gave Faith the poisoned champagne, had a routine way of handing over a glass that someone who knew his habits would be able to predict.