"So much I learned partly from village gossip and partly from my own observation. There are no better instruments than discharged servants with a grievance, and I was lucky enough to find one. I call it luck, but it would not have come my way had I not been looking out for it. As Baynes remarks, we all have our systems. It was my system which enabled me to find John Warner, late gardener of High Gable, sacked in a moment of temper by his imperious employer. He in turn had friends among the indoor servants who unite in their fear and dislike of their master. So I had my key to the secrets of the establishment. "Curious people, Watson! I don't pretend to understand it all yet, but very curious people anyway. It's a double-winged house, and the servants live on one side, the family on the other. There's no link between the two save for Henderson's own servant, who serves the family's meals. Everything is carried to a certain door, which forms the one connection. Governess and children hardly go out at all, except into the garden. Henderson never by any chance walks alone. His dark secretary is like his shadow. The gossip among the servants is that their master is terribly afraid of something. 'Sold his soul to the devil in exchange for money,' says Warner, 'and expects his creditor to come up and claim his own.' Where they came from, or who they are, nobody has an idea. They are very violent. Twice Henderson has lashed at folk with his dog-whip, and only his long purse and heavy compensation have kept him out of the courts. "Well, now, Watson, let us judge the situation by this new information. We may take it that the letter came out of this strange household and was an invitation to Garcia to carry out some attempt which had already been planned. Who wrote the note? It was someone within the citadel, and it was a woman. Who then but Miss Burnet, the governess? All our reasoning seems to point that way. At any rate, we may take it as a hypothesis and see what consequences it would entail. I may add that Miss Burnet's age and character make it certain that my first idea that there might be a love interest in our story is out of the question. "If she wrote the note she was presumably the friend and confederate of Garcia. What, then, might she be expected to do if she heard of his death? If he met it in some nefarious enterprise her lips might be sealed. Still, in her heart, she must retain bitterness and hatred against those who had killed him and would presumably help so far as she could to have revenge upon them. Could we see her, then and try to use her? That was my first thought. But now we come to a sinister fact. Miss Burnet has not been seen by any human eye since the night of the murder. From that evening she has utterly vanished. Is she alive? Has she perhaps met her end on the same night as the friend whom she had summoned? Or is she merely a prisoner? There is the point which we still have to decide.