was busily engaged reading and answering letters. She started up when she saw Vandeleur and uttered an exclamation of surprise.
"What has happened?" she asked.
Vandeleur went up to her and took her hand.
"Do not be alarmed," he said, "for I have come to put all your fears to rest. Now, please, listen to me. When you visited Madame Sara with your sister, did you go for medical advice?"
The colour rushed into her face.
"One of my teeth ached," she answered. "I went to her about that. She is, as I suppose you know, a most wonderful dentist. She examined the tooth, found that it required stopping, and got an assistant, a Brazilian, I think, to do it."
"And your tooth has been comfortable ever since?"
"Yes, quite. She had one of Edith's stopped at the same time."
"Will you kindly sit down and show me which was the tooth into which the stopping was put?"
She did so.
"This was the one," she said, pointing with her finger to one in the lower jaw. "What do you mean? Is there anything wrong?"
Vandeleur examined the tooth long and carefully. There was a sudden rapid movement of his hand, and a sharp cry from Mrs. Selby. With the deftness of long practice, and a powerful wrist, he had extracted the tooth with one wrench. The suddenness of the whole thing, startling as it was, was not so strange as his next movement.
"Send Mrs. Selby's maid to her," he said, turning to her husband; "then come, both of you, into the next room."
The maid was summoned. Poor Mrs. Selby had sunk back in her chair, terrified and half fainting. A moment later Selby joined us in the dining-room.
"That's right," said Vandeleur; "close the door, will you?"
He opened his black bag and brought out several instruments. With one he removed the stopping from the tooth. It was quite soft and came away easily. Then from the bag he produced a small guinea-pig, which he requested me to hold. He pressed the sharp instrument into the tooth, and opening the mouth of the little animal placed the point on the tongue. The effect was instantaneous. The little head fell on to one of my hands—the guinea-pig was dead. Vandeleur was white as a sheet. He hurried up to Selby and wrung his hand.
"Thank Heaven!" he said, "I've been in time, but only just. Your wife is safe. This stopping would hardly have held another hour. I have been thinking all night over the mystery of your sister-in-law's death, and over every minute detail of evidence as to how the poison could have been administered. Suddenly the coincidence of both sisters having had their teeth stopped struck me as remarkable. Like a flash the solution came to me. The more I considered it the more I felt that I was right; but by what fiendish cunning such a scheme could have been conceived and executed is still beyond my power to explain. The poison is very like hyoscine, one of the worst toxic-alkaloids known, so violent in its deadly proportions that the amount that would go into a tooth would cause almost instant death. It has been kept in by a gutta-percha stopping, certain to come out within a month, probably earlier, and most probably during mastication of food. The person would die either immediately or after a very few minutes, and no one would connect a visit to the dentist with a death a month afterwards."
What followed can be told in a very few words. Madame Sara was arrested on suspicion. She appeared before the magistrate, looking innocent and beautiful, and managed during her evidence completely to baffle that acute individual. She denied nothing, but declared that the poison must have been put into the tooth by one of the two Brazilians whom she had lately engaged to help her with her dentistry. She had her suspicions with regard to these men soon afterwards, and had dismissed them. She believed that they were in the pay of José Aranjo, but she could not tell anything for certain. Thus Madame escaped conviction. I was certain that she was guilty, but there was not a shadow of real proof. A month later Silva died, and Selby is now a double millionaire.
