"Any theory could account for his presence," said the Spaniard, shrugging his shoulders and walking towards the window as though heartily tired of my objections. "One is that he was some burglar who had got the office that the colonel had left the flat, and had disguised himself to resemble the master, had walked in at the front door and personated him over-night, and had been assassinated in error. Such cases of impersonation are much more common than people imagine, but they have such ludicrous, as well as tragic, results that they seldom, if ever, get into the police courts. Another theory--and to me not at all a bad one--is that the whole business has been engineered by some secret society for a purpose that will eventually become apparent. As you know, there are plenty of secret organisations in London that do not content themselves with mystic signs and passwords and occasional extravagances in the shape of nitro-glycerine and dynamite. I know there is a branch of the Spanish `Friends of Liberty' in England, for instance; and I am sure if they have got some hint from Mexico about the discovery of those manuscripts they will stop at nothing--not even a crime like this--to frighten off Colonel Napier." "Well, I had better leave it," I said at last, with a sigh, throwing the paper on to the floor and joining my companion at the casement. "After all, you are really the leader of this expedition, and you have a right to require of me that I shall pay some attention to your conclusions." "Yes; leave it," repeated Casteno. "Remember, you are only one man with one brain and one pair of hands. You can't do everything in a maze that has such extraordinary ramifications as this. I tried alone, remember, and failed; and, first, I had to get your help, and then Mr Cooper-Nassington's, and heaven alone knows where we shall end. But this brings me to another point, Glynn," he went on, with increasing earnestness. "I want you not to approach Miss Doris until this flying machine experiment is over. It is quite natural of you to wish to do so, I admit, but I want you to consider my interests a little for a day or two, and to refrain." "I see," I said meditatively. "You are afraid something might happen, some injudicious word of hers, some careless act, which might scare off some of the people we want to keep blind to our movements, eh?" "Yes," answered Casteno; "but that's not all. You must recollect, too, that the people who are not for us are against us. It is not really to the Napier interest that your side should win. They are fighting, in my opinion, on the side of the authorities as represented by the Foreign Secretary and the earl. Well, let them, that's all, and only when we've won let us put our heads above the hedge."