A detective story from the series about the adventures of Erast Fandorin. Anisy Tyulpanov, a young man of twenty, entered service as an agent in the Gendarme Department. But Tyulpanov, poor fellow, could not hold on to his good, lucrative post. Lieutenant Colonel Sverchinsky himself declared him a hopeless agent and, in general, a weakling. So he was transferred to the very lowest position — that of courier. And could Anisy have imagined that chance would bring him together with the famous Erast Fandorin, and that he would become his assistant in the most tangled case of the “Jack of Spades”?