"Look at it this way," said Quarles. "Dr. Smith, who was a man of no importance, and had done little in his profession, took a weak-minded patient into his house. Where he lived at the time we do not know. This patient may have had friends who died; possibly he was left on the doctor's hands without adequate payment. We will suppose, further, that this patient had peculiarities--a love of being important, of being somebody, of being flattered, and above all of loving a secret to an abnormal degree. Except to those who knew him well, he appeared a normal individual under ordinary circumstances. We get to facts when we say that Smith had schemes in his head. He contemplated insuring his life for a large sum, and we will assume that he meant to reap the benefit himself. How did he go to work? He took a house at Riversmouth, where he was unknown, and in due course arrived there with his wife, who was privy to his scheme, and his one patient." "It was not until he had settled in Riversmouth that he had patients," I said. "That fact is established." "Let me get to my point, Wigan. It was necessary that the doctor should have an assistant, so we get Evans at Riversmouth. The doctor, by flattery, by pandering to his love of secrecy, suggested to his patient that he should call himself Dr. Smith. So the scheme was floated. It must necessarily be a work of time, during which the doctor must live. He took three other patients, who were well cared for and looked after, chiefly by Evans. Through Ferguson, who I suggest became a partner in the scheme, the insurance was effected. When the time was ripe, Dr. London being dead, this patient, who had come to be known as Dr. Smith by the few people who had caught sight of him, was murdered, drowned, in the way I have suggested, by the doctor. The wife remained to claim the money. So we watch her, and through her we shall presently catch her husband." "And the assistant?" I asked. "I grant, Wigan, that the facts supporting my theory are not so strong as I could wish; that is why we cannot act, why we must wait. We have a master criminal to deal with in Mr. Smith, who remains in hiding for a time. What he calls himself now I cannot say, but we know him as Patrick Evans." We had to wait a long time. Mrs. Smith even had the temerity to commence legal proceedings against the insurance company, and then, probably for the purpose of getting coached upon some difficult point, she had a secret meeting with Evans in a restaurant in Soho. Husband and wife and the solicitor Ferguson were arrested. Mrs. Smith and Ferguson were brought to trial and sentenced as accessories before the fact, but the doctor succeeded in committing suicide in his cell. CHAPTER XII THE AFFAIR OF THE STOLEN GOLD "So you have your wish, Wigan," said the professor, one evening a few weeks later, discussing a sensational case which was almost without parallel in the history of London.