In the final scene of the Chillicothe Theatre Company’s Aug. 8-9 production of the hilarious Brooklyn, N.Y.-based 1940s Joseph Kesselring play, “Arsenic and Old Lace,” spinster sisters Abby (Ronni Clark, center) and Martha Brewster (Sue Bachman, right) prepare to serve unsuspecting Mr. Witherspoon (Dave Rogers), superintendent of the Happy Dale sanitarium, a fatal glass of their homemade elderberry wine laced with arsenic and two other poisons. …