Agatha Raisin S04E04 - A Spoonful of Poison, Part 1

Agatha, Roy, and Sarah attend the Fruit Preserve Festival, where Charles and James are two of the judges for the jam competition, and DCI Wilkes is one of the competitors. After a few rounds of tastings, however, the judges start to act out, hallucinating-and Dr. Stevens, believing she can fly, jumps from the roof. DCI Wilkes employs Agatha to find the killer, as he's currently in the frame.