This bit of cunning on her part, was not surprising, considering what a man Agdolo was, and, as we shall see, it proved of great advantage to her, but in a way she least expected. The Marchese d'Agdolo had paid his farewell visit to the Elector, and received leave to depart. Frederick Augustus had not the remotest suspicion that his mother was playing a crooked part, and he seemed heartily satisfied with the negociation, and made the Marquis a present. On September 15, 1776, Agdolo was intending to start from Dresden, on his return to Munich, and the evening before leaving he spent at the house of a friend, Ferber, playing cards. Little did he suspect that whilst he was winning one stake after another at the table, the greatest stake of all was lost. That evening, whilst he was playing cards, a courier arrived from Berlin, in all haste, and demanded to see the Elector in person, instantly, as he had a communication of the utmost importance to make from Frederick II. He was admitted without delay, and the whole of his mother's plot was detailed before the astonished Elector. "The originals of these transcripts," said the courier, "are in the hands of the Marchese d'Agdolo, let him be arrested, and a comparison of the documents made." The Privy Council was at once assembled, and the papers received from Frederick II. were laid before it. The members voted unanimously that the Marquis should be arrested, and General Schiebell was entrusted with the execution of the decree. No surprise was occasioned by the entry of General Schiebell into the house of Ferber. It was a place of resort of the best society in Dresden; but when the General announced that he had come to make an arrest, many cheeks lost their colour. "In the name of his Serene Highness the Elector," said the General, "I make this man my prisoner," and he laid his hand on the shoulder of Agdolo, who had served under him in the Seven Years' War. He was taken at once to his own lodgings, where his desks and boxes--already packed for departure--were opened, and all his papers removed. The same night, under a strong guard, he was transported at 10 o'clock, to Königstein. In that strong fortress and state prison, perched on an isolated limestone crag, the rest of his life was to be spent in confinement. But the Marchese, like a crafty Italian, had made his preparations against something of the sort; for among his papers was found a communication addressed by him to the Elector, revealing the whole plot. It was undated. If the search of his rooms and the discovery of his papers had been made earlier, the Elector might have believed that the man had really intended to betray his mistress, but, he had postponed the delivery of the communication too late.[17]