Like many girls Pattie and Sheila Reilly like horses. One day Pattie takes a ride on a stray pony. An unknown man surprises them and very unwisely fires a shot in the air. The sudden bang startles the horse and makes it bolt. Pattie is thrown off and her scared kid sister flags down PC Walker, who gets both of them to Dr. Trent's surgery. He also has his own, more romantic reason to see the attractive doctor. When Walker tries to find both the owner of the pony and the shooter he suddenly finds himself investigating a series of horse thefts. His life is not made any easier by Joyce Jowett, who complains to the police about a bad smell and noisy lorries from the house at the end of her road. Sergeant Miller has referred her to the town hall because it is not a police matter, but the battleaxe pesters the life out of Walker instead. Aunt Peggy gets mad at Oscar Blaketon for barring her and David from the Aidensfield Arms for playing poker.