Who Threw the Barbitals in Mrs. Fletcher's Chowder? (S04E12)

S04E01 A Fashionable Way to Die S04E02 When Thieves Fall Out S04E03 Witness for the Defense S04E04 Old Habits Die Hard S04E05 The Way To Dusty Death S04E06 It Runs In The Family S04E07 If It's Thursday, It Must Be Beverly S04E08 Steal Me a Story S04E09 Trouble in Eden S04E10 Indian Giver S04E11 Doom with a View S04E12 Who Threw the Barbitals in Mrs. Fletcher's Chowder? S04E13 Harbinger of Death S04E14 Curse of the Daanav S04E15 Mourning Among the Wisterias S04E16 Murder Through the Looking Glass S04E17 A Very Good Year for Murder S04E18 Benedict Arnold Slipped Here S04E19 Just Another Fish Story S04E20 Showdown in Saskatchewan S04E21 Deadpan S04E22 The Body Politic