A series of illegal knuckle fights has been taking place all over North Riding and sergeant Blaketon asks his constables to look out for Irishman Michael O'Leary, who is suspected of being behind them. Not surprisingly O'Leary is spotted at Claude Greengrass's place. Martin Lessor is attacked in his home, but the attacker Victor Kellerman is much more eager to see the case in court than Lessor is. To complicate matters Lessor, who is a diabetic, will only allow Alex Ferrenby to look into his medical files, but Ferrenby is away on a fishing trip.

Arthur Wakesfield surprises a burglar and tries to scare him off, but gets a heart attack from which he later dies in the process. The burglar, John Tinniswood, hardly fares any better, when he comes home because his wife nearly tears his head off, but she still gives him a false alibi when he is arrested for the crime. Wakefield's widow is sure it was him though and starts to follow him around anywhere he goes. Special constable Hector Cowley poses problems of another kind. He is overly officious and a pain in the neck to everybody from sergeant Blaketon and down. And to a lot of other people for that matter. Cowley counts on winning a prize for his gooseberries at the local fair, but somebody destroys them on the night before.