"The third party," continued Ronald, "being Mr. Oliver Nisbet, who visited the Coopers on the following night. He must have had some motive for this visit, for it is not likely--after what you learned from Dr. Cooper's lips of the feeling he entertained toward Mr. Nisbet--that this gentleman would have paid his accomplice a visit in which there was no direct motive. I speak of them as accomplices because there is no doubt in my mind on the point. Dr. Cooper was bribed to give a false death certificate, false for the reason that he was not in a position to give a true one, and for this service Mr. Nisbet paid him, and made promises (according to Dr. Cooper) which he did not fulfill. Whether these promises were or were not as Dr. Cooper hinted is of small moment in what we are discussing, the one thing certain being that Dr. Cooper labored under a sense of injury, and believed himself to have been wronged. It is more than probable that, in some way, Dr. Cooper conveyed this impression to Mr. Nisbet, and that he was aware of it. This must have occurred years ago, and shortly afterward Dr. Cooper loses sight of his employer, and has no means of communicating with him. If he had known where to write to him he would certainly have done so, in his state of poverty, and would most likely have thrown out some kind of threat. During this interval Mr. Nisbet keeps himself hidden from the man who has served him at a critical time; he has no use for him; all evidence of the crime (the nature of which has yet to be discovered) he has committed is destroyed, and there is only one person in the world who can throw the remotest suspicion upon him; that person is Dr. Cooper, and even he, if he dared take open action, would find himself implicated in the consequences. So matters rest for a considerable time, and we come now to the present. It is on Sunday only that you are informed by the private inquiry agent you employed that Mr. Nisbet had returned to London and was staying at the Métropole. Again crops up the hidden motive for his return. Was it to visit the house in Lamb's Terrace in which the crime was committed? Was it to seek Dr. Cooper for the purpose of obtaining his assistance in a fresh crime to be committed on foreign soil? Conjecture only will assist us here, for we know nothing; but conjecture, put to a logical use, may lead to the right conclusion. I assert that Mr. Nisbet's visit to London was expressly made either to go to Lamb's Terrace or to see Dr. Cooper; certainly for one of these reasons, perhaps for both. When you learn that he is in London you are on your way to Dr. Cooper's house; you find him; you have a singular conversation with him; you return home, and my uncle informs you of the discovery of the clothes he has found in the attic cupboard. That those clothes belonged to Beatrice and the servant cannot be disputed. On Monday morning, after my uncle leaves you to find a temporary home for poor little Barbara, you also leave the fated house several hours, and you take especial care to deposit the clothes in what you believe to be a place of safety; unfortunately, as it happened, in the place in which they were first discovered. Now, who knows of that place of deposit? You, my uncle, and Mr. Nisbet. During your absence Mr. Nisbet obtains easy admission to the house, goes straight to the attic cupboard, and bears away with him the garments which, by devious circumstantial evidence, might be a danger to him. While he is in the house some signs therein lead him to suspect that it is not absolutely untenanted, and he sets watch upon it in the night. Looking from the window of the room occupied by you and my uncle you see Mr. Nisbet standing in the garden in a watchful, observant attitude; and as he stands there the spectral monitor which has set this inquiry at work gives you a sign--an unmistakable sign from the spiritual throne of justice. Rank heresy or blind fatuity might misinterpret this sign; to you, to my uncle, to me, it is as clear as sunlight. It declared this man to be guilty of a horrible crime; it was like the writing on the wall. Satisfied or not, Mr. Nisbet leaves Lamb's Terrace, and goes to South Lambeth to see Dr. Cooper, of whose movements during the years that have passed he has had full knowledge. Mr. Nisbet is not only a dangerous man and a criminal, he is a man of resource and powerful intellect, and such a man leaves little to chance. Closeted with Dr. Cooper and his wife, he hears of your visit to him the previous evening; he worms out of his accomplice all that the man can recollect of your conversation with him; and he scents danger. Now, as I have said, whether he went to Dr.