Visiting Robert's niece Peggy and her husband Malcolm, Hetty learns that their son Tom has been expelled from school after an Ecstasy tablet was found on him. Hetty is convinced that he was framed and, with the headmaster's cooperation, goes undercover as a dinner lady, meeting Karl 'Bomber' Ashby, the school bully and his gang who have taken revenge on Tom after he has refused them money. Geoffrey also goes undercover as a pupil but after his identity is revealed Hetty has to rescue him.
—don @ minifie-1