Roald Dahl shows his great creative talent in making Mary Maloney the wife of a policeman. She has learned a great deal about how police think and operate, and this knowledge helps her commit the perfect crime. Furthermore, the fact that the police regard Patrick Maloney as "one of ours" brings many more investigators to the scene of the crime than would have otherwise been the case. They stay longer, too, because they are intent on solving this crime. And with many men working late in her house, Mary has no trouble disposing of the murder weapon by feeding it to the investigators. Ordinarily these policemen would not have sat down to a meal in a victim's home, but they decide it is okay in this case because Mary, as a cop's wife, is also "one of ours."
Mary is described as a very simple, domestic woman who is devoted to her husband.
For her, this was always a blissful time of day. She knew he didn't want to speak much until the first drink was finished, and she, on her side, was content to sit quietly, enjoying his company after the long hours alone in the house. She loved to luxuriate in the presence of this man, and to feel--almost as a sunbather feels the sun--that warm male glow that came out of him to her when they were alone together. She loved him for the way he sat loosely in a chair, for the way he came in a door, or moved slowly across the room with long strides. She loved the intent, far look in his eyes when they rested on her, the funny shape of the mouth, and especially the way he remained silent about his tiredness, sitting still with himself until the whisky had taken some of it away.
Her loving devotion will stand her in good stead after the murder because no one will suspect that such a loving, devoted wife could commit such a crime. This excessive love, however, is the reason Patrick wants a divorce. She is too loving, too possessive, too concerned about his comfort. She is a nurturing, motherly type of woman, but her mothering is suffocating her husband. She is six months pregnant, and no doubt she would have transferred some of her mothering to her baby and given her husband some breathing room. Perhaps Patrick would have been wise to put up with her over-attentiveness for just a few more months. It is not at all uncommon for women to transfer their affections to their babies, which is exactly why nature has given most of them these nurturing instincts.
Mary thinks that by waiting on her husband like a slave and by taking such a strong interest in everything he says and does, she will be able to retain his affection. But she is doing just the opposite of what she intends. Dahl deliberately refrains from quoting exactly what Patrick tells his wife when he informs her that he wants a divorce, but the main reason must be that he is sick and tired of their suffocating relationship.
Dahl did not want to indicate, for example, that Patrick was having an affair with another woman. That could be found out and would suggest a strong motive for Mary to have killed him. Dahl characterizes Mary through her dialogue and actions, while at the same time illustrating what it is about her that makes Patrick want to escape from her. She says such things as:
"I'll get it!" she cried, jumping up.
"Darling, shall I get your slippers?"
"Darling," she said. "Would you like me to get you some cheese?"
"But, darling, you must eat!"
We like Mary better after she stops being a doormat and plans the perfect crime.