Van der Valk is asked to discreetly trace Jean-Claude Marschal, the disappeared heir to a business fortune, and follows him to Innsbruck, Strasbourg and a village in the Vosges, benefitting from the cooperation of German, Austrian and French police colleagues. He discovers Marschal dead in a suicide pact reminiscent of the Mayerling incident. He then tracks Marschal's wife Anne-Marie to Biarritz and the Spanish border, where, despite having previously tried to seduce him, she shoots him.