Pietr the Lett had for years been clocked across the European frontiers by Interpol. Who was he, this international swindler with the skin of a chameleon? Was he Oswald Oppenheim, friend of multi-millionaires? Or Olaf Swann, a Norwegian merchant officer down at Fécamp? Or Fédor Yurovich, a down-and-out Russian drunk? Or could he have been the twisted corpse they found on the Pole Star express when it drew into Paris?

It cost Maigret one of his best inspectors — and a ducking in the sea — to unravel one of the most tortuous puzzles of identity he had ever handled.