Hastings renews his friendship with Poirot and involves him in the mysterious poisoning of the mistress of a manor house married to a man twenty years her junior.
At a flower show, an older woman in a wheelchair approaches Poirot, gives him an empty seed packet, and asks him to visit her the next day. When Poirot arrives the next day, the woman is dead, murdered with poison.
Poirot and Hastings attend the Victory Ball, a popular costume party. During the festivities, one of the guests is found stabbed to death, and another succumbs to a drug overdose the next day.