Hercule Poirot's quiet supper in a London coffee house is interrupted when a young woman confides to him that she is about to be murdered. She is terrified, but begs Poirot not to find and punish her killer. Once she is dead, she insists, justice will have been done. Later, Poirot learns that three guests at a London hotel have been murdered. Could there be a connection with the frightened woman?