Try This One for Size — James Hadley Chase

When Claude Kendrick, owner of a shadily run art gallery in Paradise City, is approached by Ed Haddon, the King of art thieves, to find a buyer for a priceless icon of Catherine the Great, he believes his dreams have come true. Herman Radnitz, a multimillionaire, is the man prepared to pay six million dollars for the stolen art, but there's a catch: Radnitz wanted the icon delivered to Zurich as part of the deal. To his joy, Kendrick learns of a couple travelling to Europe. All he has to do is make sure the icon is planted on them unawares. But he's picked the wrong couple ...