* Irony and Misdirection: The entire story is built on a foundation of irony. The reader is led to believe that Mary Maloney is a loving, innocent housewife, while the truth is revealed in a shocking twist. The initial focus on Mary's pregnancy and her love for her husband creates a sense of normalcy that is shattered when the truth is revealed.
* Deception and Manipulation: Mary's cleverness and calculated actions, including her calmness, the way she leads the police astray, and her seemingly innocent actions, contribute to the suspense. She expertly manipulates the situation, leading the officers to believe her while secretly harboring the truth.
* Dramatic Irony: The reader is privy to Mary's knowledge of the crime, while the police remain oblivious. This creates a sense of anticipation and tension, as the reader knows the truth and waits for the inevitable reveal.
* The Unexpected Twist: The climax of the story is the revelation that Mary has used the frozen leg of lamb as the murder weapon. This unexpected turn of events is both shocking and darkly humorous, leaving the reader breathless and questioning the nature of Mary's character.
* The Final Scene: The ending is both chilling and ambiguous. Mary's calm and composed demeanor, her final statement about her "lovely" dinner, and the police officers happily consuming the evidence of the crime, add a final layer of suspense and leave the reader contemplating the chilling consequences of Mary's actions.
By expertly weaving these elements together, Dahl creates a captivating and suspenseful story that keeps the reader guessing until the very last sentence.