The Chief Officer had grave matters to communicate to his Highness: a plot to murder her Excellency the Landhofmeisterin had been discovered, and from intercepted papers it would appear that the conspirators also aimed at the Duke himself. It seemed that many influential persons were implicated. The design was to induce his Highness to abdicate in favour of the Erbprinz, during whose minority Forstner was to be Premier, and the Duchess Johanna Elizabetha Regent of Wirtemberg. This portion of the conspiracy could be dealt with easily, but the murderous intent upon the Landhofmeisterin took a more serious aspect, as the Secret Service agents had procured information which led the Chief Officer to infer that the would-be assassins were actually in, or near, Ludwigsburg. It was, however, impossible to arrest every stranger on mere suspicion, for both Ludwigsburg and Stuttgart were full of country gentlemen who had been commanded to appear at the Mask Ball. At mention of Forstner, his Highness went to his bureau to seek his erstwhile friend's letter. In vain he searched in drawer and secret panel. The letter had vanished. The four cadets, who stood sentry at the door of the Duke's apartment, were questioned; they had seen none enter. His Highness's private waiting-men were examined, and the soldiers of the guard who stood in the lower antehall. All answered that no one had passed through. The Chief Officer of the Secret Service himself had watched the entrance of the Corps de Logis during the preceding evening. The Duke searched his bureau once more. He was greatly disturbed. Open warfare, a hand-to-hand combat, he said, were child's play to the horror of this lurking enemy, who evidently had access even to the private bureau. Zollern was requested to come and speak with the Duke; his advice was asked. 'Have you mentioned the matter to the Landhofmeisterin? She is very wise, and may be able to suggest some explanation,' said Zollern. No; his Highness had not seen her Excellency. Then a sudden suspicion came to Eberhard Ludwig. She wished to see the letter; could she have purloined it? 'Do you know if the Landhofmeisterin left the ballroom during the last evening?' he asked Zollern. No; the old Prince had observed her Excellency constantly, and she had not been absent from the dancing-hall, save for a few moments which she passed on one of the balconies in the company of a black domino, whose identity Monseigneur de Zollern had been unable to ascertain. Serenissimus dismissed his suspicions with relief. It is pain to doubt those we love. Zollern took his leave, and the Duke desired the Secret Service officer to retire. He would ask her Excellency's advice in private. The Landhofmeisterin was summoned to attend his Highness on important business. After some little delay she arrived. Passing up the grand stairs, she was ceremoniously ushered into his Highness's presence.