Who is the protagonist in "Lamb to the Slaughter"? Fully describe what he/she is like?

The protagonist of the story is Mary Maloney, a peaceful
housewife, married and pregnant to a policeman, Patrick
Maloney.

 Her gentle acceptance of her ordinary life
changes when her husband announces that the marriage is over, but that she will need to
keep quiet about the separation for the sake of his job. He shows no compassion for her
emotional reaction, nor for the fact that she is pregnant with their
child.

 She kills her husband in a moment of dissociation –
clubbing him with a frozen leg of lamb. It is her primitive desire to survive and
protect her child which causes her to coolly plan her alibi and to cover her crime,
unwittingly abetted by her husband’s colleagues. She indeed keeps any scandal from
emerging, although the information she hides is not quite what her husband had
envisaged.