In August, 1918, he had discovered a toxic product of extraordinary virulence, not a gas, but a tasteless and odorless liquid containing harmful bacteria. These bacteria showed great resistance against heat and cold and were able to propagate and disseminate themselves with incredible rapidity through living creatures, rats, earth worms, birds, cattle, dogs, fleas, that might feed upon them or come in contact with them. The deadliness of this product was so great, as appeared from laboratory tests, that it was believed all human life might be exterminated in a region intensively inoculated (from airplanes or guns) with the liquid. This was only a possibility, but it was an enormously important possibility. A report on this formidable discovery had been prepared by Dr. Owen for the Washington authorities with such extreme secrecy that the chemical formula for the liquid had been indicated simply by the letters X K C, the product being referred to as X K C liquid. Moreover, the only person, except Dr. Owen, in possession of the full facts touching this discovery was Captain Herrick who had assisted the doctor in his investigations. Herrick had been cautioned to guard this secret as he would his life, since there was involved in it nothing less than the possibility of preventing future wars through the power of its potential terribleness. The bearing of all this upon our narrative was presently made clear as the conflict developed between tortured Penelope and the psychic in Roberta Vallis' studio. For some moments the two women eyed each other in hostile silence, which was broken presently by the sound of footsteps in the hall. "Ah! Here comes your doctor!" mocked the fair creature on the divan. "Now watch Fauvette!" The door opened and Dr. Owen, followed by Herrick, both grave-faced, entered the apartment. Christopher turned anxiously to Seraphine: "What has happened? Is she better?" Mrs. Walters shook her head, but when the young officer looked at Penelope his fears were lessened, for she (was it from dissimulation or weariness?) gave no indication of her recent frenzy, but seemed to be resting peacefully against the cushions. "Let's have a little more light here," said Dr. Owen, and he turned on the electrics. "I'm afraid you have overtaxed your strength, Mrs. Wells." Penelope answered gently with perfect self-possession: "I'm afraid I have, doctor, I'm sorry to give you so much trouble." And she smiled sweetly at Herrick. The specialist drew up a chair and studied his patient thoughtfully. There was an added austerity in his usual professional manner. "Captain Herrick tells me that you made some rather strange remarks just now?" he said tentatively. Mrs. Wells met him with a look of half amused understanding. "Did I?" she answered carelessly, and as she spoke she took up a pencil and made formless scrawls on a sheet of paper. "I suppose he refers to my calling him a fool. It is a little unusual, isn't it?"