Ludovic Travers had never come across a more ingenious fraud - three of them, in fact. All were perpetrated in only twenty-four hours. One was in Liverpool, the second and third in Southampton and London. The same two people, posing as an American married couple, had purchased a diamond ring at each of three jewellery stores, paying for all three with beautifully forged traveller's cheques to the tune of about two thousand pounds. The thieves had then done a highly successful vanishing act.
Shortly after Ludovic Travers is called in on the case, he is diverted from it by the search for a missing heir, one of the twin grandsons of an old friend. The twin on the scene - the Heavenly Twin, Travers calls him - is apparently doing very well. The other has definitely gone wrong, and has also disappeared.
On the missing twin's trail, Travers encounters yet another diversion: a jewel robbery in a country house in Hampshire. And then two more forged cheques turn up. Are they red herrings or pieces of the same puzzle?