While hot on the heels of serial coupon-racketeer Gordon Ginner, Chief Inspector MacDonald of Scotland Yard receives word of an intriguing incident up in Lancashire – the summer cottage of local farmer Giles Hoggett has been broken into, with an assortment of seemingly random items missing which include a complete reel of salmon line, a large sack, and two iron dogs from his fireplace. What first appears to Insp. MacDonald as a simple break-in quickly spirals into a mystery of contested land grabs for fishing between farmers, made all the more enticing to MacDonald when a body is then found in the river – the body of Gordon Ginner. It's up to Insp. MacDonald, aided by the locals of Lunesdale, to determine who broke into Hoggett's cottage, where his irons dogs have gone, and how Ginner met his watery end.