 Nick and Jo Rowan return from their honeymoon in Spain. They find out that he has been made acting sergeant at the Ashfordly police station, while Blaketon has taken over the post office. A fair is visiting Aidensfield and one of its main attractions is the wall of death and its riders Dirk and Liam. Especially 15-year old Tracey Knight is fascinated by Dirk who has promised her a spot on the show. Dirk is seriously injured when he crashes off the wall during practice. The police soon find out it was not an accident. Another attraction is the mouse show, which Greengrass  lurcher Alfred decides by eating the favourite owned by the very unpopular Trevor Lammas. The next day Greengrass finds his dog lying on the floor with all signs of poisoning and accuses Lammas, who starts to have a series of small mishaps.