Thirty-two of the best international players participate in the Pretenders Tournament at the Hôtel des Ambassades. At the start of his match Mikael Koroleva, one of the favorite players, suddenly had a nosebleed and collapses, struck down by poison. On site, Astrid and Raphaël try to find the culprit among the players. They soon discover that Shun Naito is cheating against his new opponent via his watch connected to artificial intelligence. Shortly after, Naito was found dead below the hotel: he had been beaten and thrown out of the window.
