Detective-Inspector Napoleon Bonaparte agrees to help a colleague in the matter of the disappearance of George Loftus, a farmer whose car was found abandoned near the world's longest fence, in the wheat country of Western Australia. He immediately suspects murder but can’t find the evidence to confirm it. Loftus's wife seems concerned about him, but his handsome hired man is an enigma. It is not until Bony becomes absorbed in the second mystery of Mr Jelly, an amateur criminologist who himself often disappears on secret business, that he finds the key to the strange goings-on in this seemingly ordinary farming community.