Then Rudolph handed Countess Marie a steel casket which he asked her to take charge of, saying: “It is imperative that it should not be found in my possession, for at any moment the Emperor may order my personal belongings to be seized.” And then:— “How long am I to keep this dreadful thing in my possession?” “Until I ask for it,” answered Rudolph, “or until someone else asks for it. If it should come to that,” he added gravely, “you must know how to act. There is one person who knows the secret of this casket, and he alone has the right (failing me) to ask for its return.” “His name?” “Never mind his name. You can deliver it to the person who can tell you four letters. Write them down now, and repeat them after me. Listen: R.I.U.O.” It is as mysterious, and apparently as meaningless, as any conspiracy in a melodrama or a comic opera; and it may be permissible to mention here that Countess Marie was warned, before her story was printed, that nobody would believe it. She nevertheless insisted. She could not be positive that the casket was of steel, because it was wrapped up in a covering which she did not undo. But it was a casket—or at any rate a box of some kind; and it was heavy. She afterwards handed it over, in circumstances to which we shall come, to the mysterious person who gave the mysterious password; and she related all this in London in a very matter-of-fact manner, which gave her interlocutors the impression that, if her story were not true, it would have been absolutely beyond her capacity to invent it. But, true or false, what relation did it bear to the necessity for a private interview with Mary at the Hofburg? That is what Countess Marie does not explain; and her failure to see that any explanation is required and will be demanded may perhaps be taken as an indirect proof of her _bona fides_. An inventor would not have failed to supply the missing link, which neither a criminal investigator nor a sensational novelist would have any difficulty in conjecturing. Granted that Rudolph had involved himself in a political plot—whether to get himself crowned King of Hungary or for any other purpose—then the whole of the evidence relating to the plot cannot have been contained in the mysterious steel casket. Some further evidence—a letter or some other scrap of paper—must have been in Mary Vetsera’s possession. She must have been holding it over Rudolph’s head as an instrument of blackmail—demanding, perhaps, that he should divorce his wife and marry her; or, at all events, he must have suspected her of the intention to do so, and have wanted to get the document back from her. On that assumption—but on no other—the political necessity of the interview on which Rudolph insisted is clear.