In “Lamb to the Slaughter,” the complex symbolism of the lamb emphasizes the story’s theme of the violence of devotion. Mary is a traditional, adoring wife who caters to her husband’s comfort. For example, she painstakingly prepares a welcome for his return home from work each day:

The room was warm and clean, the curtains drawn, the two table lamps alight—hers and the one by the empty chair opposite. On the sideboard behind her, two tall glasses, soda water, whiskey. Fresh ice cubes in the Thermos bucket.

After he walks in, she takes his coat, fixes him a drink, and sits attentively, waiting to address his needs. When she notices him finishing his first drink, she jumps up to pour him a second one and fetch his slippers. Observing that he looks tired, she offers to cook dinner at home instead of enjoying their weekly night out at a restaurant.

The lamb symbolizes Mary because she is pure and gentle. Like a lamb, she is faithful and helplessly ignorant of her husband's infidelity and her future as castoff wife and single mother. Completely devoted to her husband, she is shocked when he admits to an affair. In fact, Mary becomes a sacrificial lamb, a metaphor for an innocent person or animal sacrificed for someone else; in this case, she pays or atones for her husband’s sin of adultery. He cavalierly expects her to disappear without protest and to shoulder responsibility of their unborn baby alone. He tells her,

And I know it’s kind of a bad time to be telling you, but there simply wasn’t any other way. Of course I’ll give you money and see you’re looked after. But there needn’t really be any fuss. I hope not anyway. It wouldn’t be very good for my job.

The idiom “lamb to slaughter” describes a party who unknowingly enters danger or walks into trap. Interestingly, Mary’s husband becomes a lamb to slaughter, albeit a twisted lamb. Although not innocent like a lamb, he is ignorant of impending danger, which he unwittingly brought upon himself.

Ironically, a frozen lamb leg is the weapon Mary uses to kill her husband. She

simply walked up behind him and without any pause she swung the big frozen leg of lamb high in the air and brought it down as hard as she could on the back of his head.

Mary strikes him out of shock and rage equivalent to and caused by the depth of her devotion. His death by bludgeoning results from his callous dismissal of her devotion. Interestingly, the brutality of his murder contrasts the icy calmness of Mary moving forward.

The violence of the crash, the noise, the small table overturning, helped bring her out of her shock. She came out slowly, feeling cold and surprised, and she stood for a while blinking at the body, still holding the ridiculous piece of meat tight with both hands.

All right, she told herself. So I’ve killed him.

Her violent act transforms her from a meek wife into a clear-minded, strategic, and self-preserving woman. Mary is no longer a lamb, and the frozen lamb leg saves her from becoming a lamb to slaughter. Her husband’s infidelity and desertion are no longer threats. She is freed from her oppressive marriage into the role of a sympathetic widow. And the lamb leg is the actual tool for committing a literal slaughter of the lamb to which she devoted herself—her unfaithful and unsuspecting husband.