Just before Violet Fernsley is to be hanged for the murder of abusive husband Ivan Fernsley, whose corpse wasn't found, she persuades father Brown to try prove her innocence and gets a three days reprieve by claiming to expect child, from lover-jailer Charlie Denham. However her clue that 'Peter is the key' seems a wild goose chase, as it refers to as still missing Polish seasonal laborer Piotr, her lover who offered to run away with her. Brown finds indications that several murder victims may have been fed to the pigs at the in-laws farm, which cripple widow Ethel Fernsley's eldest surviving son Archie Fernsley, an ambitious simpleton, runs with rude brother Wilfred. Another crime is committed at the firm, and Brown nor Sid or even his employer, lady Felicia, are safe themselves.
—KGF Vissers