When Robert goes to stay with his brother Frank in Weston-Super-Mare, Hetty visits Frank's daughter Peggy in Bodley Bay. Peggy's son, Tom, has been suspended from school after an ecstasy tablet was planted in his blazer pocket. Hetty goes undercover as a dinner lady at Tom's school to find out the truth. Her extended stay means a visit from Geoff with a change of clothes and, having just passed his driving test, he takes up mechanic Janet's offer to do a trial run in a VW Beetle that she is trying to sell. As soon as he arrives, Geoff is roped in on the case. In disguise as a new pupil, he joins the gang of boys responsible for framing Tom, but soon finds himself in serious trouble. It is only Hetty's quick thinking that saves him from a potentially nasty end. However, all ends safely as Tom is vindicated and Geoff finds himself the owner of a newly sprayed VW - in more or less perfect working order.